C语言实现字符串拼接和字符串拷贝

字符串拼接：

#include
#include
#include

char *str_contact(const char *,const char *);

char *str_contact(const char *str1,const char *str2)
{
	char *result = (char*) malloc(strlen(str1) + strlen(str2) + 1);
    if(!result)
    {
    	printf("Error: malloc failed in concat! \n");
    	exit(EXIT_FAILURE);
    }

    char *temp = result;
    while(*str1 != '\0')
    {
    	*result++ = *str1++;
    }

    while((*result++ = *str2) != '\0')
    {
    	；
    }

    return temp;
}


int main(void)
{
	char *ch1 = "string_";
	char * ch2 = "_contact";
	char *result = NULL;
	result = str_contact(ch1,ch2);
	print("result = %s\n",result);
	free(result);
	result = NULL;
	return 0;
}

字符串拷贝：

#include
#include
#include

char *strcpy(char *dst,const char *src)
{
	assert(*dst != NULL && *src!=NULL);
	char *temp = dst;
	while(*src!='\0')
	{
		*dst++ = *src++;
	}
	*dst = '\0';

	return temp;
}

int main(void)
{
	char *ch1 = "str_cpy";
	char *ch2;
	char *result = strcpy(ch2,ch1);
	printf("result = %s\n",result);
	free(result);
	result = NULL;
	return 0;
}