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《The C Programming Language》答案（第五章）
P1
getch.c
/** * getch.c * written by swy */#include #define BUFSIZE 114char buf[BUFSIZE];int bufp = 0;int getch(){ return (bufp>0)?buf[--bufp]:getchar();}void ungetch(int c){ if(bufp>=BUFSIZE) printf("buffer overflow!\n"); else buf[bufp++]=c;}
getch.h
/** * getch.h * written by swy */int getch();void ungetch(int);
main.c
#include #include #include "getch.h"#define SIZE 14int getint(int* pn){ int c, sign, c2; while (isspace(c = getch())) /* skip white space */ ; if (!isdigit(c) && c != EOF && c != '+' && c != '-') { ungetch(c); /* it is not a number */ return 0; } sign = (c == '-') ? -1 : 1; if (c == '+' || c == '-') { if (!isdigit(c2 = getch())) { ungetch(c2); ungetch(c); return 0; } else c = c2; } for (*pn = 0; isdigit(c); c = getch()) *pn = 10 * *pn + (c - '0'); *pn *= sign; if (c != EOF) ungetch(c); return c;}int main(void){ int n, array[SIZE], r; for (n = 0; n < SIZE && (r = getint(&array[n])) != EOF; n++) { if (r) printf("you input a number: %d\n", array[n]); else printf("it is not a number.\n"); } return 0;}
P2
/** * getch.c * written by swy */#include #define BUFSIZE 114char buf[BUFSIZE];int bufp = 0;int getch(){ return (bufp>0)?buf[--bufp]:getchar();}void ungetch(int c){ if(bufp>=BUFSIZE) printf("buffer overflow\n"); else buf[bufp++] = c;}
/** * getch.h * written by swy */int getch();void ungetch(int);
/** * main.c * written by swy */#include #include #include "getch.h"#define SIZE 14int getfloat(double *pn){ double power, base, epower; int c, sign, c2, emark, exponent; while (isspace(c = getch())) /* skip white space */ ; if (!isdigit(c) && c != EOF && c != '+' && c != '-') { ungetch(c); /* it is not a number */ return 0; } sign = (c == '-') ? -1 : 1; if (c == '+' || c == '-') { if (!isdigit(c2 = getch())) { ungetch(c2); ungetch(c); return 0; } else c = c2; } for (*pn = 0.0; isdigit(c); c = getch()) *pn = 10.0 * *pn + (c - '0'); if (c == '.') c = getch(); for (power = 1.0; isdigit(c); c = getch()) { *pn = 10.0 * *pn + (c - '0'); power *= 10.0; } epower = 1; if (c == 'e' || c == 'E') { emark = c; c = getch(); base = c == '-' ? 0.1 : 10.0; if (c == '+' || c == '-') { if (!isdigit(c2 = getch())) { ungetch(c2); ungetch(c); } else c = c2; } else if (!isdigit(c)){ ungetch(c); ungetch(emark); } for (exponent = 0; isdigit(c); c = getch()) { exponent = 10 * exponent + (c- '0'); } while (exponent-- > 0) epower *= base; } *pn *= sign / power * epower; if (c != EOF) ungetch(c); return c;}int main(void){ int n; double array[SIZE], r; for (n = 0; n < SIZE && (r = getfloat(&array[n])) != EOF; n++) { if (r) printf("you input a number: %g\n", array[n]); else printf("it is not a number.\n"); } return 0;}
P3
#include #define MAXLINE 1024void str_cat(char* s,char* t){ while (*s) ++s; while (*s++ = *t++) ;}int getchars(char* s,int max){ int c, i, l; for (i = 0, l = 0; (c = getchar()) != EOF && c != '\n'; ++i) if (i < max - 1) { *s++ = c; ++l; } *s = '\0'; return l;}int main(void){ char *s, *t; printf("input string s: \n"); while (getchars(s, MAXLINE) == 0) ; printf("input string t: \n"); while (getchars(t, MAXLINE) == 0) ; str_cat(s, t); printf("cat: %s\n", s); return 0;}
P4
#include #define MAXLINE 1024int strend(char* s,char* t){ int sl, tl; sl = tl = 0; while (*s++) sl++; while (*t++) tl++; if (sl >= tl) { s -= tl; t -= tl; while (*s++ == *t++) if (!*s) return 1; } return 0;}int getchars(char* s,int max){ int c, i, l; for (i = 0, l = 0; (c = getchar()) != EOF && c != '\n'; ++i) if (i < max - 1) { *s++ = c; ++l; } *s = '\0'; return l;}int main(){ char* s; char* t; printf("Please Enter:\n"); while(getchars(s,MAXLINE)==0) ; while (getchars(t, MAXLINE) == 0) ; printf("string t is%s at the end of the string s.\n", strend(s, t) ? "" : " not"); return 0;}
P5
strncpy
#include void mstrncpy(char* s,char* t,int n){ while(n-->0&&(*s++=*t++)) ; *s = '\0';}int main(){ char* t = "yeshouxianbei114514"; char* s; mstrncpy(s,t,11); printf("%s\n",s); return 0;}
strncat
/** * strncat.c * written by swy */#include void mstrncat(char* s,char* t,int n){ while(*s) ++s; while(n-->0&&*t){ *(s++) = *(t++);//this line is buggy in Windows, but can work normally on the original Unix } *s = '\0';}int main(){ char* s; char* t; s = "114514"; t = "1919810"; mstrncat(s,t,4); printf("%s\n",s); return 0;}
strncmp
/** * strncmp * written by swy */#include int mstrncmp(char* s,char* t,int n){ for(;n-->0&&*s==*t;++s,++t) if(*s=='\0'||n==0) return 0; return *s-*t;}int main(){ char* s; char* t; s = "114514"; t = "1919810"; printf("%d\n",mstrncmp(s,t,5)); return 0;}
P6
🐎🐴
P7
/** * lines.h * written by swy **/#define MAXLINES 55#define MAXLEN 108int _getline(char* ,int);int readlines(char* lineptr[],int nlines);void writelines(char* lineptr[],int nlines);
/** * lines.c * written by swy **/#include #include #include "lines.h"int readlines(char* lineptr[],int maxlines){ int len, nlines; char line[MAXLEN]; nlines = 0; while ((len = _getline(line, MAXLEN)) > 0) if (nlines >= maxlines) return -1; else { line[len-1] = '\0'; /* delete newline */ strcpy(lineptr[nlines++], line); } return nlines;}void writelines(char* lineptr[],int nlines){ int i; for(i=0;i
/** * qsort.h * written by swy **/void qsort(char *lineptr[],int left,int right);
/** * qsot.c * written by swy * traitor Fang Fang biss **/#include void qsort(char *v[],int left,int right){ int i, last; void swap(char *v[], int i, int j); if (left >= right) /* do nothing if array contains */ return; /* fewer than two elements */ swap(v, left, (left + right)/2); last = left; for (i = left+1; i <= right; i++) if (strcmp(v[i], v[left]) < 0) swap(v, ++last, i); swap(v, left, last); qsort(v, left, last-1); qsort(v, last+1, right);}void swap(char *v[],int i,int j){ char* tmp; tmp = v[i]; v[i] = v[j]; v[j] = tmp;}
/** * main.c * written by swy **/#include #include "lines.h"#include "qsort.h"char* lineptr[MAXLINES]int main(void){ int nlines; /* number of input lines read */ int i; char s[MAXLINES][MAXLEN]; for (i = 0; i < MAXLINES; ++i) { *(lineptr + i) = s[i]; } if ((nlines = readlines(lineptr, MAXLINES)) >= 0) { qsort(lineptr, 0, nlines-1); writelines(lineptr, nlines); return 0; } else { printf("error: input too big to sort\n"); return 1; }}
P8
#include static char daytab[2][13] = { { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}, { 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};int day_of_year(int year,int month,int day){ int i,leap; if (month < 1 || month > 12 || day < 1) return 0; leap = year % 4 == 0 && year % 100 != 0 || year % 400 == 0; if (day > daytab[leap][month]) return 0; for (i = 1; i < month; i++) day += daytab[leap][i]; return day;}int month_day(int year,int yearday,int* pmonth,int* pday){ int i, leap; leap = year % 4 == 0 && year % 100 != 0 || year % 400 == 0; if (yearday < 1 || yearday > (leap ? 366 : 365)) return 0; for (i = 1; yearday > daytab[leap][i]; i++) yearday -= daytab[leap][i]; *pmonth = i; *pday = yearday; return 1;}int main(){ int year, month, day, yearday; int doy, pmonth, pday; year = 2012; month = 2; day = 29; doy = day_of_year(year, month, day); if (doy) printf("%d-%d-%d: day %dth of the year.\n", year, month, day, doy); else printf("%d-%d-%d: invalid!\n", year, month, day); year = 2012; month = 6; day = 31; doy = day_of_year(year, month, day); if (doy) printf("%d-%d-%d: day %dth of the year.\n", year, month, day, doy); else printf("%d-%d-%d: invalid!\n", year, month, day); year = 2012; yearday = 60; doy = month_day(year, yearday, &pmonth, &pday); if (doy) printf("day %dth of year %d is %d-%d.\n", yearday, year, pmonth, pday); else printf("day %dth of year %d do not exsits!\n", yearday, year); year = 2012; yearday = 367; doy = month_day(year, yearday, &pmonth, &pday); if (doy) printf("day %dth of year %d is %d-%d.\n", yearday, year, pmonth, pday); else printf("day %dth of year %d do not exsits!\n", yearday, year); return 0;}
P9
#include static char daytab[2][13] = { { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}, { 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};int day_of_year(int year,int month,int day){ int i,leap; if(month<1||month>12||day<1) return 0; leap = year%4==0&&year%100!=0||year%400==0; if(day>*(*(daytab+leap)+month)) return 0; for(i=1;i (leap?366:365)) return 0; for(i=1;yearday>*(*(daytab+leap)+i);i++) yearday-=*(*(daytab+leap)+i); *pmonth=i; *pday=yearday; return 1;}int main(){ int year, month, day, yearday; int doy, pmonth, pday; year = 2012; month = 2; day = 29; doy = day_of_year(year, month, day); if (doy) printf("%d-%d-%d: day %dth of the year.\n", year, month, day, doy); else printf("%d-%d-%d: invalid!\n", year, month, day); year = 2012; month = 6; day = 31; doy = day_of_year(year, month, day); if (doy) printf("%d-%d-%d: day %dth of the year.\n", year, month, day, doy); else printf("%d-%d-%d: invalid!\n", year, month, day); year = 2012; yearday = 60; doy = month_day(year, yearday, &pmonth, &pday); if (doy) printf("day %dth of year %d is %d-%d.\n", yearday, year, pmonth, pday); else printf("day %dth of year %d do not exsits!\n", yearday, year); year = 2012; yearday = 367; doy = month_day(year, yearday, &pmonth, &pday); if (doy) printf("day %dth of year %d is %d-%d.\n", yearday, year, pmonth, pday); else printf("day %dth of year %d do not exsits!\n", yearday, year); return 0;}
P10
#include #include #include #include #include #define NUMBER '0'#define MAXVAL 114int sp = 0;double val[MAXVAL];void push(double f){ if (sp < MAXVAL) val[sp++] = f; else printf("stack overflow! %g\n", f);}double pop(){ if(sp>0) return val[--sp]; else{ printf("stack empty!\n"); return 0.0; }}int main(int argc, char *argv[]){ int type, c; double op2; printf("Usage example: expr 1 1 4 + p\n"); while (--argc > 0) { if (!isdigit(c = **++argv) && strlen(*argv) == 1) type = c; else type = NUMBER; switch (type) { case NUMBER: push(atof(*argv)); break; case '+': push(pop() + pop()); break; case 'p': push(pop() * pop()); break; case '-': op2 = pop(); push(pop() - op2); break; case '/': op2 = pop(); if (op2 != 0.0) push(pop() / op2); else printf("error: zero divisor\n"); break; case '%': op2 = pop(); if (op2 != 0.0) push(fmod(pop(), op2)); else printf("error: zero divisor\n"); break; default: printf("error: unknown command\n"); break; } } printf("= %g\n", pop()); return 0;}
P11
entab
/** * entab.c * written by swy **/#include #include #define MAXLINE 1024#define DEFAULTTABWIDTH 4#define MAXTABSTOPS 10int getchars(char* s,int max){ int c, i, l; for (i = 0, l = 0; (c = getchar()) != EOF && c != '\n'; ++i) if (i < max - 1) { *s++ = c; l++; } *s = '\0'; return l;}void entab(char* s1,char* s2,int w[]){ int i,j,c,blanks,k; int blanksenough; i = 0; k = 0; while ((c = *s1) != '\0') { if (c == ' ') { blanksenough = 1; if (w[k] == 0) k = 0; blanks = w[k] - i % w[k]; k++; for (j = 1; j < blanks; ++j){ if (*(s1 + j) != ' ') { blanksenough = 0; break; } } if (blanksenough) { *s2++ = '\t'; s1 += blanks; i += blanks; } else { *s2++ = c; i++; ++s1; } } else { *s2++ = c; i++; ++s1; } } *s2++ = '\0';}int main(int argc,char** argv){ char s1[MAXLINE]; char s2[MAXLINE]; int w[MAXTABSTOPS + 1]; int i, tab, j; if (argc > MAXTABSTOPS) argc = MAXTABSTOPS; j = 0; for (i = 2; i <= argc; ++i) { tab = atoi(*++argv); if (tab > 0) w[j++] = tab; } if (i == 2) w[j++] = DEFAULTTABWIDTH; w[j] = 0; printf("Usage example: entab 2 4 6\n"); printf("Input some characters, then press enter:\n"); while (getchars(s1, MAXLINE) == 0) ; entab(s1, s2, w); printf("entab result:\n%s\n", s2); return 0;}
detab
/** * detab.c * written by swy **/#include #include #define MAXLINE 1024#define DEFAULTTABWIDTH 4#define MAXTABSTOPS 10int getchars(char* s,int max){ int c, i, l; for (i = 0, l = 0; (c = getchar()) != EOF && c != '\n'; ++i) if (i < max - 1) { *s++ = c; l++; } *s = '\0'; return l;}void detab(char* s1,char* s2,int w[]){ int j,l,c,blanks,k; l=0; k=0; while ((c = *s1++) != '\0') { if (c == '\t') { if (w[k] == 0) k = 0; blanks = w[k] - l % w[k]; k++; for (j = 0; j < blanks; ++j) { *s2++ = ' '; l++; } } else { *s2++ = c; l++; } } *s2 = '\0';}int main(int argc,char** argv){ char s1[MAXLINE]; char s2[MAXLINE]; int w[MAXTABSTOPS + 1]; int i, tab, j; if (argc > MAXTABSTOPS) argc = MAXTABSTOPS; j = 0; for (i = 2; i <= argc; ++i) { tab = atoi(*++argv); if (tab > 0) w[j++] = tab; } if (i == 2) w[j++] = DEFAULTTABWIDTH; w[j] = 0; printf("Usage example: detab 2 4 6\n"); printf("Input some characters, then press enter:\n"); while (getchars(s1, MAXLINE) == 0) ; detab(s1, s2, w); printf("detab result:\n%s\n", s2); return 0;}
P12
entab
/** * entab.c * written by swy **/#include #include #define MAXLINE 1024#define DEFAULTSTARTCOL 1#define DEFAULTTABWIDTH 8int getchars(char* s,int max){ int c, i, l; for (i = 0, l = 0; (c = getchar()) != EOF && c != '\n'; ++i) if (i < max - 1) { *s++ = c; l++; } *s = '\0'; return l;}void entab(char* s1,char* s2,int col,int w){ int i,j,c,blanks; int blanksenough; i = 0; while ((c = *s1) != '\0') { if (c == ' ' && i >= col - 1) { blanksenough = 1; blanks = w - i % w; for (j = 1; j < blanks; ++j){ if (*(s1 + j) != ' ') { blanksenough = 0; break; } } if (blanksenough) { *s2++ = '\t'; s1 += blanks; i += blanks; } else { *s2++ = c; i++; ++s1; } } else if (c == '\t') { *s2++ = c; i += w - i % w; ++s1; } else { *s2++ = c; i++; ++s1; } } *s2++ = '\0';}int main(int argc,char** argv){ char s1[MAXLINE]; char s2[MAXLINE]; int m, n, m2, n2; m = DEFAULTSTARTCOL; n = DEFAULTTABWIDTH; while (--argc > 0) { argv++; if (**argv == '-') { if ((m2 = atoi(++*argv)) > 0) m = m2; } else if (**argv == '+') { if ((n2 = atoi(++*argv)) > 0) n = n2; } } printf("Usage example: entab -2 +8\n"); printf("Input some characters, then press enter:\n"); while (getchars(s1, MAXLINE) == 0) ; entab(s1, s2, m, n); printf("entab result:\n%s\n", s2); return 0;}
detab
/** * detab.c * written by swy **/#include #include #define MAXLINE 1024#define DEFAULTSTARTCOL 1#define DEFAULTTABWIDTH 8int getchars(char* s,int max){ int c, i, l; for (i = 0, l = 0; (c = getchar()) != EOF && c != '\n'; ++i) if (i < max - 1) { *s++ = c; l++; } *s = '\0'; return l;}void detab(char* s1,char* s2,int col,int w){ int j, l, c, blanks; l = 0; while ((c = *s1++) != '\0') { if (c == '\t') { blanks = w - l % w; if (l >= col - 1) { for (j = 0; j < blanks; ++j) { *s2++ = ' '; l++; } } else { *s2++ = c; l += blanks; } } else { *s2++ = c; l++; } } *s2 = '\0';}int main(int argc,char** argv){ char s1[MAXLINE]; char s2[MAXLINE]; int m,n,m2,n2; m = DEFAULTSTARTCOL; n = DEFAULTTABWIDTH; while (--argc > 0) { argv++; if (**argv == '-') { if ((m2 = atoi(++*argv)) > 0) m = m2; } else if (**argv == '+') { if ((n2 = atoi(++*argv)) > 0) n = n2; } } printf("Usage example: detab -2 +8\n"); printf("Input some characters, then press enter:\n"); while (getchars(s1, MAXLINE) == 0) ; detab(s1, s2, m, n); printf("detab result:\n%s\n", s2); return 0;}
P13
/** * lines.h * written by swy **/#define MAXLINES 55#define MAXLEN 114int _getline(char* ,int);int readlines(char* lineptr[],int nlines);int writelines(char* lineptr[],int nlines);
/** * alloc.h * written by swy **/char *alloc(int);void afree(char *p);
/** * lines.c * written by swy **/#include #include #include "alloc.h"#include "lines.h"int readlines(char* lineptr[],int maxlines){ int len, nlines; char *p, line[MAXLEN]; nlines = 0; while ((len = _getline(line, MAXLEN)) > 0) if (nlines >= maxlines || (p = alloc(len)) == NULL) return -1; else { line[len-1] = '\0'; /* delete newline */ strcpy(p, line); lineptr[nlines++] = p; } return nlines;}void writelines(char* lineptr[],int nlines){ int i; for(i=0;i
/** * alloc.c * written by swy **/#include #define ALLOCSIZE 114514static char allocbuf[ALLOCSIZE];static char* allocp = allocbuf;char* alloc(int n){ if(allocbuf+ALLOCSIZE-allocp>=n){ allocp+=n; return allocp-n; }else return 0;}void afree(char* p){ if(p>=allocbuf&&p
/** * main.c * written by swy **/#include #include #include "lines.h"#define DEFAULTTAILNUM 10char* lineptr[MAXLINES];int main(int argc, char **argv){ int nlines; /* number of input lines read */ int tailnum, p; tailnum = DEFAULTTAILNUM; if (argc > 1 && **++argv == '-') { if ((p = atoi(++(*argv))) > 0) tailnum = p; } if ((nlines = readlines(lineptr, MAXLINES)) >= 0) { if (nlines < tailnum) tailnum = nlines; writelines(lineptr + nlines - tailnum, tailnum); return 0; } else { printf("error: input too big\n"); return 1; }}
P14
/** * lines.h * written by swy **/#define MAXLINES 50#define MAXLEN 114int _getline(char* ,int);int readlines(char* lineptr[],int nlines);void writelines(char* linepter[],int nlines);
/** * alloc.h * written by swy **/char* alloc(int);void afree(char* p);
/** * alloc.c * written by swy **/#include #define ALLOCSIZE 114514static char allocbuf[ALLOCSIZE];static char* allocp = allocbuf;char* alloc(int n){ if (allocbuf + ALLOCSIZE - allocp >= n) { /* it fits */ allocp += n; return allocp - n; /* old p */ } else /* not enough room */ return 0;}void afree(char *p) /* free storage pointed to by p */{ if (p >= allocbuf && p < allocbuf + ALLOCSIZE) allocp = p;}
/** * lines.c * written by swy **/#include #include #include "alloc.h"#include "lines.h"int readlines(char* lineptr[],int maxlines){ int len, nlines; char *p, line[MAXLEN]; nlines = 0; while ((len = _getline(line, MAXLEN)) > 0) if (nlines >= maxlines || (p = alloc(len)) == NULL) return -1; else { line[len-1] = '\0'; /* delete newline */ strcpy(p, line); lineptr[nlines++] = p; } return nlines;}void writelines(char* lineptr[],int nlines){ int i; for(i=0;i
/** * qsort.h * written by swy **/void qsort(void* lineptr[],int left,int right,int (*comp)(void*,void*),int order);
/** * qsort.c * written by swy **/#include void qsort(void* v[],int left,int right,int(*comp)(void*,void*),int order){ int i, last; void swap(void *v[], int, int); if (left >= right) /* do nothing if array contains */ return; /* fewer than two elements */ swap(v, left, (left + right)/2); last = left; for (i = left+1; i <= right; i++) if (order && (*comp)(v[i], v[left]) < 0) swap(v, ++last, i); else if (!order && (*comp)(v[i], v[left]) > 0) swap(v, ++last, i); swap(v, left, last); qsort(v, left, last-1, comp, order); qsort(v, last+1, right, comp, order);}void swap(void* v[],int i,int j){ void *temp; temp = v[i]; v[i] = v[j]; v[j] = temp;}
/** * numcmp.h * written by swy **/int numcmp(char*,char*);
/** * numcmp.c * written by swy **/#include int numcmp(char* s1,char* s2){ double v1, v2; v1 = atof(s1); v2 = atof(s2); if (v1 < v2) return -1; else if (v1 > v2) return 1; else return 0;}
/** * main.c * written by swy **/#include #include "string.h"#include "lines.h"#include "qsort.h"#include "numcmp.h"char* lineptr[MAXLINES];int main(int argc, char **argv){ int nlines; /* number of input lines read */ int numeric = 0; /* 1 if numeric sort */ int order = 1; /* 1 if sorting in increasing order*/ int c; while (--argc > 0 && *(*++argv) == '-') { while ((c = *++(*argv)) != '\0') { switch (c) { case 'n': numeric = 1; break; case 'r': order = 0; break; default: break; } } } if ((nlines = readlines(lineptr, MAXLINES)) >= 0) { qsort((void**) lineptr, 0, nlines-1, (int (*)(void*,void*))(numeric ? numcmp : strcmp), order); writelines(lineptr, nlines); return 0; } else { printf("error: input too big to sort\n"); return 1; }}
P15
/** * alloc.h * written by swy **/char* alloc(int);void afree(char* p);
/** * alloc.c * written by swy **/#include #include "alloc.h"#define ALLOCSIZE 114514static char allocbuf[ALLOCSIZE];#define char* allocp = allocbuf;char* alloc(int n){ if (allocbuf + ALLOCSIZE - allocp >= n) { /* it fits */ allocp += n; return allocp - n; /* old p */ } else /* not enough room */ return 0;}void afree(char* p){ if (p >= allocbuf && p < allocbuf + ALLOCSIZE) allocp = p;}
/** * lines.h * writen by swy **/#define MAXLINES 50#define MAXLEN 114int _getline(char*,int);int readlines(char* lineptr[],int nlines);void writelines(char* lineptr[],int nlines);
/** * lines.c * written by swy **/#include #include #include "alloc.h"#include "lines.h"int readlines(char* lineptr[],int maxlines){ int len,nlines; char *p, line[MAXLEN]; nlines = 0; while ((len = _getline(line, MAXLEN)) > 0) if (nlines >= maxlines || (p = alloc(len)) == NULL) return -1; else { line[len-1] = '\0'; /* delete newline */ strcpy(p, line); lineptr[nlines++] = p; } return nlines;}void writelines(char* lineptr[],int nlines){ int i; for(i=0;i
/** * cmp.h * written by swy **/int numcmp(char*,char*);int strcmpignore(char*,char*);
/** * cmp.c * written by swy **/#include #include int numcmp(char* s1,char* s2){ double v1,v2; v1 = atof(s1); v2 = atof(s2); if (v1 < v2) return -1; else if (v1 > v2) return 1; else return 0;}int strcmpignore(char* s1,char* s2){ for (; tolower(*s1) == tolower(*s2); ++s1, ++s2) if (*s1 == '\0') return 0; return tolower(*s1) - tolower(*s2);}
/** * qsort.h * written by swy **/void qsort(void* lineptr[],int left,int right,int (*comp)(void*,void*),int order);
/** * qsort.c * written by swy **/#include void qsort(void* v[],int left,int right,int (*comp)(void*,void*),int order){ int i, last; void swap(void *v[], int, int); if (left >= right) /* do nothing if array contains */ return; /* fewer than two elements */ swap(v, left, (left + right)/2); last = left; for (i = left+1; i <= right; i++) if (order && (*comp)(v[i], v[left]) < 0) swap(v, ++last, i); else if (!order && (*comp)(v[i], v[left]) > 0) swap(v, ++last, i); swap(v, left, last); qsort(v, left, last-1, comp, order); qsort(v, last+1, right, comp, order);}void swap(void* v[],int i,int j){ void* tmp; tmp = v[i]; v[i] = v[j]; v[j] = tmp;}
/** * main.c * written by swy **/#include #include "string.h"#include "lines.h"#include "qsort.h"#include "cmp.h"char* lineptr[MAXLINES];int main(int argc, char **argv){ int nlines; /* number of input lines read */ int numeric = 0; /* 1 if numeric sort */ int order = 1; /* 1 if sorting in increasing order */ int ignorecase = 0; /* 1 if case insensitive */ int c; while (--argc > 0 && *(*++argv) == '-') { while ((c = *++(*argv)) != '\0') { switch (c) { case 'n': numeric = 1; break; case 'r': order = 0; break; case 'f': ignorecase = 1; break; default: break; } } } if ((nlines = readlines(lineptr, MAXLINES)) >= 0) { qsort((void**) lineptr, 0, nlines-1, (int (*)(void*,void*))(numeric ? numcmp : (ignorecase ? strcmpignore : strcmp)), order); writelines(lineptr, nlines); return 0; } else { printf("error: input too big to sort\n"); return 1; }}
P16
/** * alloc.h * written by swy **/char* alloc(int);void afree(char* p);
/** * alloc.c * written by swy **/#include #define ALLOCSIZE 114514static char allocbuf[ALLOCSIZE];static char* allocp = allocbuf;char *alloc(int n) { if (allocbuf + ALLOCSIZE - allocp >= n) { /* it fits */ allocp += n; return allocp - n; /* old p */ } else /* not enough room */ return 0;}void afree(char* p){ if(p>=allocbuf&&p
/** * lines.h * written by swy **/#define MAXLINES 50#define MAXLEN 114int _getline(char*,int);int readlines(char* lineptr[],int nlines);void writelines(char* lineptr[],int nlines);
/** * lines.c * written by swy **/#include #include #include "alloc.h"#include "lines.h"int readlines(char* lineptr[],int maxlines){ int len, nlines; char *p, line[MAXLEN]; nlines = 0; while ((len = _getline(line, MAXLEN)) > 0) if (nlines >= maxlines || (p = alloc(len)) == NULL) return -1; else { line[len-1] = '\0'; /* delete newline */ strcpy(p, line); lineptr[nlines++] = p; } return nlines;}void writelines(char* lineptr[],int nlines){ int i; for(i=0;i
/** * cmp.h * written by swy **/int numcmp(char*,char*);int strcmpignore(char*,char*);
/** * cmp.c * written by swy **/#include int numcmp(char* s1,char* s2){ double v1, v2; v1 = atof(s1); v2 = atof(s2); if (v1 < v2) return -1; else if (v1 > v2) return 1; else return 0;}int strcmpignore(char* s1,char* s2){ for (; tolower(*s1) == tolower(*s2); ++s1, ++s2) if (*s1 == '\0') return 0; return tolower(*s1) - tolower(*s2);}
/** * qsort.h * written by swy **/void qsort(void* lineptr[],int left,int right,int (*comp)(void*,void*),int order);
/** * qsort.c * written by swy **/#include void qsort(void* v[],int left,int right,int (*comp)(void*,void*),int order){ int i, last; void swap(void *v[], int, int); if (left >= right) /* do nothing if array contains */ return; /* fewer than two elements */ swap(v, left, (left + right)/2); last = left; for (i = left+1; i <= right; i++) if (order && (*comp)(v[i], v[left]) < 0) swap(v, ++last, i); else if (!order && (*comp)(v[i], v[left]) > 0) swap(v, ++last, i); swap(v, left, last); qsort(v, left, last-1, comp, order); qsort(v, last+1, right, comp, order);}void swap(void* v[],int i,int j){ void* tmp; tmp = v[i]; v[i] = v[j]; v[j] = tmp;}
/** * main.c * written by swy **/#include #include #include #include "lines.h"#include "qsort.h"#include "cmp.h"int isdirectory(char* s){ return isdigit(*s)||isalpha(*s)||isspace(*s);}int strcompare(char* s1,char* s2){ if (directory) { while(*s1 != '\0' && !isdirectory(s1)) s1++; while(*s2 != '\0' && !isdirectory(s2)) s2++; if (ignorecase) { while (tolower(*s1) == tolower(*s2)) { if (*s1 == '\0') return 0; s1++; s2++; while(*s1 != '\0' && !isdirectory(s1)) s1++; while(*s2 != '\0' && !isdirectory(s2)) s2++; } return tolower(*s1) - tolower(*s2); } else { printf("dsdsd\n"); while (*s1 == *s2) { if (*s1 == '\0') return 0; s1++; s2++; while(*s1 != '\0' && !isdirectory(s1)) s1++; while(*s2 != '\0' && !isdirectory(s2)) s2++; } return *s1 - *s2; } } else { if (ignorecase) { return strcmpignore(s1, s2); } else { return strcmp(s1, s2); } }}int strcompare(char *s1, char *s2);int isdirectory(char *s);char *lineptr[MAXLINES]; /* pointers to text lines */int ignorecase = 0; /* 1 if case insensitive */int directory = 0; /* 1 if sorting in directory order */int main(int argc, char **argv){ int nlines; /* number of input lines read */ int numeric = 0; /* 1 if numeric sort */ int order = 1; /* 1 if sorting in increasing order*/ int c, i; char *t; while (--argc > 0 && *(*++argv) == '-') { while ((c = *++(*argv)) != '\0') { switch (c) { case 'n': numeric = 1; break; case 'r': order = 0; break; case 'f': ignorecase = 1; break; case 'd': directory = 1; break; default: break; } } } if ((nlines = readlines(lineptr, MAXLINES)) >= 0) { qsort((void**) lineptr, 0, nlines-1, (int (*)(void*,void*))(numeric ? numcmp : strcompare), order); writelines(lineptr, nlines); return 0; } else { printf("error: input too big to sort\n"); return 1; }}
第五章 完
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