C/C++对char*字符串的操作

C/C++自写的字符串操作函数

//连接字符串
void Strcat(char *before, char *after);
//复制字符串
void Strcpy(char *newstr, const char *oldstr);
//获取字符串长度
size_t Getlenth(const char *str);
//转化为小写
void Strlwr(char *str);
//转化为大写
void Strupr(char *str);
//比较字符串是否相等
bool Strcmp(const char *str1, const char *str2);
//将字符串2插入字符串2的指定位置
void StrInsert(const char *str1, const char *str2, int point);

实现部分

#include <stdio.h>
#include <stdlib.h>
#include "teststring.hpp"
void Strcat(char *before, char *after)
{
    while (*before != '\0')
    {
        before++;
    }

    while (*after != '\0')
    {
        *before = *after;
        before++;
        after++;
    }
    *before = '\0';
}

void Strcpy(char *newstr, const char *oldstr)
{
    while (*oldstr != '\0')
    {
        *newstr = *oldstr;
        newstr++;
        oldstr++;
    }
    *newstr = '\0';
}

size_t Getlenth(const char *str)
{
    size_t length = 0;
    if (str != NULL)
    {
        while (*str != '\0')
        {
            length++;
            str++;
        }
    }
    return length;
}

//转化为小写
void Strlwr(char *str)
{
    while (*str != '\0')
    {
        if (*str <= 'Z' && *str >= 'A')
        {
            *str -= 'A' - 'a';
        }
        str++;
    }
}

//转化为大写
void Strupr(char *str)
{
    while (*str != '\0')
    {
        if (*str <= 'z' && *str >= 'a')
        {
            *str -= 'a' - 'A';
        }
        str++;
    }
}

//比较字符串是否相等
bool Strcmp(const char *str1, const char *str2)
{
    if ((*str1 != '\0') && (*str2 != '\0'))
    {
        return true;
    }
    while ((*str1 != '\0') && (*str2 != '\0'))
    {
        if (*str1 - *str2 != 0)
        {
            return false;
        }
    }
    return true;
}

//将字符串2插入字符串2的指定位置
void StrInsert(char *str1, char *str2, int point)
{
    char *str1_buff = str1;
    size_t str1length = Getlenth(str1);
    size_t str2length = Getlenth(str2);
    char *tempstr = new char[str1length + str2length];
    char *tempstr_buff = tempstr;
    for (int i = 0; i < point; i++)
    {
        *tempstr_buff = *str1_buff;
        tempstr_buff++;
        str1_buff++;
    }
    while (*str2 != '\0')
    {
        *tempstr_buff = *str2;
        tempstr_buff++;
        str2++;
    }
    while (*str1_buff != '\0')
    {
        *tempstr_buff = *str1_buff;
        tempstr_buff++;
        str1_buff++;
    }
    *tempstr_buff = '\0';
    Strcpy(str1, tempstr);
    delete tempstr;
}