C language-simulate database functions strcpy, strcat, strcmp

C language-simulate database functions strcpy, strcat, strcmp
1. Database strcpy function, copy a string to another string

#include<stdio.h>#include<assert.h>char* my_srtcpy( char *srt, char*src){    assert(srt);    assert(src);    char *tmp = src;    while (*src++ = *srt++)    {        ;    }    return tmp;}int main(void){    char* arr = "abcdef";    char arr1[10];    printf("%s\n",my_srtcpy(arr, arr1));}

 

Ii. Database strcat function, append a string to another string

#include<stdio.h>#include<assert.h>char* my_srtcat(char* srt,  const char* src){    assert(srt!=NULL);    assert(src!=NULL);    char *ret = srt;    while (*srt)    {        srt++;    }    while (*srt++ = *src++)    {        ;    }    return ret;}int main(void){    char arr[15] = "abcdef";    char* arr1 = "cd";    printf("%s\n", my_srtcat(arr, arr1));}

 

3. strcmp function, returns 0 if two strings str1 and str2 are equal; str1> str2 returns 1; else returns-1

#include<stdio.h>#include<assert.h>int my_srtcmp(const char*srt1, const char* srt2){    assert(srt1);    assert(srt2);    while (*srt1 == *srt2)    {        if (*srt1 == '\0')        {            return 0;        }        srt1++;        srt2++;        }    if (srt1 > srt2)    {        return 1;    }    else    {        return -1;    }}int main(void){    char *arr = "abcd";    char *arr1 = "abc";    printf("%d\n", my_srtcmp(arr, arr1));}