字符串基本处理操作:数组和指针实现 —— 不调用string函数库

数据结构 C/C++基础

自己手动实现的字符串基本处理操作
索引数组版本 array_mode.h

//统计长度  
int strlen1(const char s[])  
{  
    int i;  
    for(i = 0; s[i] != 0; i++);  
    return i;  
}  
//Copy  
char* strcpy1( char s2[], const char s1[])  
{  
    int i;  
    for(i = 0; (s2[i] = s1[i]) != 0; i++);  
    return s2;  
}  
//Compare  
int strcmp1(const char s1[], const char s2[])  
{  
    int i = 0;  
    for (; s1[i] == s2[i]; i++)  
    {  
        if (s1[i] == 0) //s1[i], s2[i] 同时为0  
        {  
            return 0;  
        }  
    }  
    return s1[i] - s2[i];  
}  
//Compare first n characters  
int strncmp1(const char s1[], const char s2[], int n)  
{  
    int i = 0;  
    for (; s1[i] == s2[i]; i++)  
    {  
        if (s1[i] == 0 || (i+1) == n)  
        {  
            return 0;  
        }  
    }  
    return s1[i] - s2[i];  
}  
//追加  
char* strcat1(char* s1, const char* s2)  
{  
    int i = 0, j = 0;  
    for ( ; s1[i] != 0; i++);  
    for ( ; (s1[i] = s2[j]) != 0; i++, j++);  
    return s1;  
}  

指针版本 pointer_mode.h

//统计长度  
int strlen2(const char* s)  
{  
    int i = 0;  
    while(*s++)  
        i++;  
    return i;  
}  
//Copy  
char* strcpy2( char *s2, const char *s1)  
{  
    while ( *s2++ = *s1++);  
    return s2;  
}  
//Compare  
int strcmp2(const char* s1, const char* s2)  
{  
    while(*s1++ == *s2++)  
    {  
        if (*(s1-1) == 0) //s1[i], s2[i] 同时为 '\0'  
        {  
            return 0;  
        }  
    }  
    return *(s1-1) - *(s2-1);  
}  
//Compare first n characters  
int strncmp2(const char* s1, const char* s2, int n)  
{  
    while(*s1++ == *s2++)  
    {  
        n--;  
        if (*(s1-1) == 0 || n == 0) //s1[i], s2[i] 同时为 '\0'  
        {  
            return 0;  
        }  
    }  
    return *(s1-1) - *(s2-1);  
}  
//追加  
char* strcat2(char* s1, const char* s2)  
{  
    while(*s1++);  
    s1--;  
    while(*s1++ = *s2++);  
    return s1;  
}  

测试函数 main.cpp

#include<stdio.h>  
#include <stdlib.h>  
#include "array_mode.h"  
#include "pointer_mode.h"  
int main()  
{  
    char str1[50] = "Hello,HIT";  
    char str2[30] = "Hello,SZIIT";  
    char str3[30], str4[30];  
    //计算字符串长度  
    printf("strlen1(str1) = %d\n", strlen1(str1));  
    printf("strlen2(str1) = %d\n", strlen2(str1));  
    //复制字符串  
    strcpy1(str3,str1);  
    printf("str3 = %s\n", str3);  
    strcpy2(str4,str1);  
    printf("str4 = %s\n", str4);  
    //比较  
    printf("strcmp1(str1, str2) = %d\n", strcmp1(str1, str2));  
    printf("strcmp1(str1, str3) = %d\n", strcmp1(str1, str3));  
    printf("strcmp2(str1, str2) = %d\n", strcmp2(str1, str2));  
    printf("strcmp2(str1, str3) = %d\n", strcmp2(str1, str3));  
    //前缀比较  
    printf("strncmp1(str1, str2) = %d\n", strncmp1(str1, str2, 6));  
    printf("strncmp2(str1, str2) = %d\n", strncmp2(str1, str2, 6));  
    //追加  
    strcat1(str1, "hehe");  
    printf("str1 = %s\n", str1);  
    strcat2(str1, "haha");  
    printf("str1 = %s\n", str1);  
    system("pause");  
    return 0;  
}