#include 
     
      #include 
      
       char *strcpy(char *strDest, const char *strSrc) {    char *address=strDest;    assert((strDest!=NULL) &&  (strSrc!=NULL));    while(*strSrc!='\0') {        *strDest++=*strSrc++;    }    *strDest='\0';    return address;}char *strcat(char *strDest, const char *strSrc) {    char *address=strDest;    assert((strDest!=NULL) &&  (strSrc!=NULL));    while(*strDest!='\0') {        strDest++;    }    while(*strSrc!='\0') {        *strDest++ =* strSrc++;    }    *strDest='\0';    return address;}nt strcmp(const char *str1,const char *str2) {    assert((*str1!='\0' && *str2!='\0'));    while (*str1 && *str2 && *str1==*str2) {        str1++;        str2++;    }    return *str1-*str2;}int new_strlen(const char *str) {    assert(str != NULL);    int len = 0;    while (*str++ != '\0') {        ++len;    }    return len;}void *memcpy(void *dst, void *src, size_t n) {    char *dp = (char*)dst;    char *sp = (char*)src;    assert((src!=0) && (dst!=0) && n>0);    while (n--) {        *(dp++) = *(sp++);    }    *dp='\0';    return dst;}void *new_memmove(void *dst, const void *src, int n) {    char *dp = (char *)dst;    char *sp = (char *)src;    assert((src != 0)&&(dst != 0) && (n > 0));    if (sp > dp || (sp+n) < dp) {        while(n--)            *(dp++)=*(sp++);        *dp='\0';    }else if (sp < dp){        sp += n;        dp += n;        *dp = '\0';        while(n--)            *(--dp) = *(--sp);    }    return dst;}int main() {    char dest[10];    char* src = "test!";    char* ret = strcpy(dest, src);    printf("Test strcpy ret is :%s\n", ret);    char cat1str[20] = "cat1";    char* cat2str = "cat2";    printf("Test strcat ret is :%s\n", strcat(cat1str, cat2str));    char *len = "len";    printf("Test strlen ret is :%d\n", new_strlen(len));    char mem_dest[20];    char* mem_src = "the src test memcpy";    printf("Test memcpy ret is :%s\n", memcpy(mem_dest, mem_src, 10));    char mv_dest[20];    char* mv_src = "the src test memmove";    printf("Test memmove ret is :%s\n", new_memmove(mv_dest, mv_src, 10));}