C语言——模拟实现库函数（strcat,strcmp,strcpy,srelen）

Posted 2023-01-30 LHlucky_2

分别模拟实现库函数
1.strcat
2.strcmp
3.strcpy
4.srelen

1.strcat

#include<stdio.h>
#include<string.h>

void Merge(char a[], char b[], int n)

    char* q = a;
    char* p = b;
    int m = 0;
    while (*q != '\\0')
        q++;
    while (m <= n) 
        *q++ = *p++;
        m++;
    
    puts(a);


int main()

    char a[100] =  0 ;
    char b[100] =  0 ;
    gets(a);
    gets(b);
    int n = strlen(b);
    Merge(a, b, n);

2.strcmp

#include <stdio.h>
#include <assert.h>

int Strcmp(const char* str1, const char* str2) 
    assert(str1 != NULL);
    assert(str2 != NULL);
    while (*str1 == *str2) 
        if (*str1 == '\\0') 
            return 0;
        
        ++str1;
        ++str2;
    
    return *str1 - *str2;

int main() 
    char str1[] = "love";
    char str2[] = "move";
    int point = Strcmp(str1, str2);
    if (point == 0) 
        printf("str1 = str2\\n");
    
    else if (point > 0) 
        printf("str1 > str2\\n");
    
    else 
        printf("str1 < str2\\n");
    
    return 0;

3.strcpy

#include<stdio.h>
#include<string.h>

void my_strcpy(char *arr_1, char *arr_2)

    while (*arr_2!=0) 
        *arr_1++ = *arr_2++;
    


int main()

    char arr_1[100] =  0 ;
    char arr_2[100] =  0 ;
    gets_s(arr_1);
    /*int a = strlen(arr_1);*/
    gets_s(arr_2);
    my_strcpy(arr_1, arr_2);
    printf("%s", arr_1);

4.srelen

#include<stdio.h>

void my_strlen(char* arr)

    int count = 0;
    while (*arr != 0) 
        arr++;
        count++;
    
    printf("%d", count);


int main()

    char arr[100] =  0 ;
    gets_s(arr);
    my_strlen(arr);