算法4.3 取一个字符串的子串

#include <stdio.h>#include <string.h>#include <stdlib.h>int SubString( char *sub, char *str, int n, int len );void main(){char sub[10],str[20],n,len,i;gets( str );scanf("%d%d",&n,&len);i = SubString( sub, str, n, len );if ( i == 0 ){printf("wrong\n");}else{printf("%s\n",sub);}}int SubString( char *sub, char *str, int n, int len ){int str_len;int i;str_len = strlen( str );if ( n > str_len || str_len== 0 || n<1)return 0;else{for ( i=0; i<len&&*(str+n+i-1); i++ ){*sub++ = *(str+n+i-1);}*sub = 0;return 1;}}