串

str.h

#ifndef _STR_H #define _STR_H typedef struct _str { char* ch; int length; }STR; STR* str_creat(char* str); int str_destory(STR* s); int str_clear(STR* s); int str_compare(STR* s, STR* t); STR* str_cantact(STR* s, STR* t); STR* str_sub(STR* s, int pos, int len); #endif 

 

str.c

#include "str.h" #include <stdio.h> #include <stdlib.h> STR* str_creat(char* str) { int i; STR* s = (STR*)malloc(sizeof(STR)); if(s == NULL) { return NULL; } for(i = 0; str[i]; ++i); s->ch = (char*)malloc((i + 1) * sizeof(char)); if(s->ch == NULL) { free(s); return NULL; } s->length = i; while(i >= 0) { s->ch[i] = str[i]; --i; } return s; } int str_destory(STR* s) { free(s->ch); free(s); return 0; } int str_clear(STR* s) { free(s->ch); s->ch = NULL; s->length = 0; } int str_compare(STR* s, STR* t) { int i; for(i = 0; i < s->length && i < t->length; i++) { if(s->ch[i] != t->ch[i]) { return s->ch[i] - t->ch[i]; } } return s->length - t->length; } STR* str_cantact(STR* s, STR* t) { int i; char* temp = NULL; temp = (char*)malloc((s->length + t->length + 1) * sizeof(char)); if(temp == NULL) { return NULL; } for(i = 0; i < s->length; i++) { temp[i] = s->ch[i]; } for(i = 0; i < t->length; i++) { temp[i + s->length] = t->ch[i]; } temp[s->length + t->length] = 0; i = s->length + t->length; str_clear(s); s->ch = temp; s->length = i; return s; } STR* str_sub(STR* s, int pos, int len) { STR* t = NULL; if(pos < 1 || pos > s->length || len < 0 || len > s->length - pos +1) { return NULL; } t = str_creat(""); str_clear(t); t->ch = (char*)malloc((len + 1) * sizeof(char)); if(t->ch == NULL) { free(t); return NULL; } t->length = len; for(--len; len >= 0; --len) { t->ch[len] = s->ch[pos - 1 + len]; } t->ch[t->length] = 0; return t; } 

 

main.c

#include "str.h" #include <stdio.h> int main(int argc, char* argv[]) { int res; STR* s = str_creat("hello"); STR* t = str_creat("hello"); printf("string = %s, length = %d/n", s->ch, s->length); if((res = str_compare(s,t)) == 0) { printf("s = t/n"); } else if(res > 0) { printf("s > t/n"); } else if(res < 0) { printf("s < t/n"); } str_clear(t); t = str_creat(" world"); str_cantact(s, t); printf("string = %s, length = %d/n", s->ch, s->length); str_destory(t); t = str_sub(s, 2, 5); printf("string = %s, length = %d/n", t->ch, t->length); str_destory(s); return 0; }