strcpy，strncpy, strlen, strcmp strcat函数实现

标签：des   io   ar   amp   c++   res   ad   har   

#include <stdio.h>
#include <assert.h>
char* strcpy(char* strDest, const char* strSrc)
{
	assert((strDest != NULL) && (strSrc != NULL));
	
	char* address = strDest;
	
	while((*strDest++ = *strSrc++) != '\0')
		NULL;

	return address;
}

char* strncpy(char* strDest, const char* strSrc, int n)
{
	assert((strDest != NULL) && (strSrc != NULL));

	char* address = strDest;
	
	while(n-- > 0)
	{
		*strDest++ = *strSrc++;
	}

	return address;
}

int strlen(const char* str)
{
	assert(str != NULL);
	
	int strlen = 0;
	
	while((*str++) != "\0")
		strlen++;

	return strlen;
}

int strcmp(const char* str1, const char str2)
{
	assert((str1 != NULL) && (str2 != NULL));

	while(*str1 && *str2 && (*str1 == *str2))
	{
		str1++;
		str2++;
	}
	
	return (*str1 - *str2)
}

char* strcat(char* strDest, const char* strSrc, int n)
{
	assert((strDest != NULL) && (strSrc != NULL));
	char* address = strDest;

	//不能用*strSest++，否则循环结束好，strDest将指向'\0'的下一个位置
	while(*strDest)	
	{
		strDest++
	}
	
	while(*strDest++ = *strSrc++)
		NULL;

	return address;
}

strcpy，strncpy, strlen, strcmp strcat函数实现,布布扣,bubuko.com

strcpy，strncpy, strlen, strcmp strcat函数实现

标签：des   io   ar   amp   c++   res   ad   har   

原文地址：http://blog.csdn.net/walkerkalr/article/details/38511201