字符串库函数总结
1、strcat
char* strcat1(char*dst,char *src) { char *addr=dst; while(*addr!='\0') addr++; while(*addr=*src) { src++;addr++; } return addr; }
2、strcmp
int strcmp1(char*str1,char* str2 ) { while(*str1&&*str2&&*str1==*str2) { str1++; str2++; } return *str1-*str2; }
3、strcpy
char *strcpy1(char* dst,char* src) { char * addr= dst; while(*src) { *addr++=*src++; } *addr='\0'; return addr; }
4、strstr
int strstr1(char* string,char*substring) { int i,j; if(string==NULL||substring==NULL) return -1; int lenstr=strlen(string); int lensub=strlen(substring); if(lenstr<lensub) return -1; for( i=0;i<lenstr-lensub;i++) { for(j=0;j<lensub;j++) { if(string[i+j]!=substring[j]) break; } if(j==lensub) return i+1; } return -1; }