#include "stdio.h" #include "stdlib.h" int mystrlen(char* dest) { int length=0; while (*dest!='\0') { length++; dest++; } return length; } char *mystrcpy(char* dest ,char* source) { char *destbak=dest; while (*source!='\0') { *dest++=*source++; } *dest='\0'; return destbak; } char* mystrcat(char* dest,char* source) { char *destbak=dest; while (*dest!='\0') { dest++; } while (*source!='\0') { *dest++=*source++; } *dest='\0'; return destbak; } int mystrcmp(char *s , char *t ) { while( *s && *t && *s == *t ) s++,t++; return *s - *t; } void main() { char str1[]={"nihao"}; char str2[]={"nihao"}; int length=mystrlen(str2); printf("str1Length=%d\n",length); //char *p=mystrcpy(str1,str2); //printf("%s\n",p); // char *pstrcat=mystrcat(str1,str2); //printf("%s\n",pstrcat); int N=mystrcmp(str1,str2); if (N==0) { printf("相等"); } else { printf("不等"); } getchar(); }