一些字符串处理函数的实现！-优快云博客

最近刚学完数组，把一些学了的字符串处理函数进行自己理解，写出了他们的一些转化程序。有出错的地方请大家指出，相互学习！

1、strcat字符串追加

size_t strcat(char * _Str1, const char * _Str2);

将参数_Str2追加到_Str1后尾

strcat字符串追加的实现：

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

//strcat字符串追加的实现
int main()
{
	char str1[100] = "hello ";
	char str2[] = "world";
	
	int len = strlen(str1);
	char *p1 = str1;
	char *p2 = str2;
	p1 = p1 + len;
	
	while (*p2)
	{
		*(p1++) = *(p2++);
	}
	*p1 = '\0';
	
	puts(str1);
	return 0;
}

2、strncat字符串有限追加

size_t strncat(char * _Str1, const char * _Str2, size_t len);

strncat字符串有限追加的实现：

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

int main()
{
	char str1[100] = "hello ";
	char str2[] = "world";
	
	int len = strlen(str1);
	char *p1 = str1;
	char *p2 = str2;
	p1 = p1 + len;
	int n;
	scanf ("%d", &n);
	
	while (n)
	{
		*(p1++) = *(p2++);
		n--;
	}
	*p1 = '\0';
	puts(str1);
	return 0;
}

3、strcmp字符串比较

int strcmp(const char * _Str1,const char * _Str2);

比较两个字符串是否相等，相等返回0，不等返回非0

strcmp字符串比较的实现：

int main()
{
	char str1[] = "workasjdksahdksahd";
	char str2[] = "world";
	char *p1 = str1;
	char *p2 = str2;
	
	while (*p1)
	{
		if(*p1 == *p2)
		{
			p1 = p1++;
			p2 = p2++;
		continue;
		}
		else
		{
			printf ("str1 != str2\n");
			break;
		}
		printf ("str1 == str2\n");
	}


	return 0;
}

4、strncmp字符串有限比较的实现：

int main()
{
	char str1[] = "workasjdksahdksahd";
	char str2[] = "world";
	char *p1 = str1;
	char *p2 = str2;
	int n;
	scanf ("%d", &n);
	
	while (n)
	{
		if(*p1 == *p2)
		{
			p1 = p1++;
			p2 = p2++;
			n--;
			if(n == 0)
			{
				printf ("str1 == str2\n");
			}
			continue;
		}
		else
		{
			printf ("str1 != str2\n");
			break;
		}
		
	}
	
	return 0;
}

5、strcop 字符串的拷贝的实现：

int main()
{
	char str1[100] = "hello";
	char str2[] = "worldkgffijhgkjhgkjh";
	
	// 拷贝实现
	char *p1 = str1;
	char *p2 = str2;
	
	while (*p2)
	{
		*(p1++) = *(p2++);
	}
	*p1 = '\0';
	
	puts(str1);
	
	return 0;
}

6、strcop 字符串的有限拷贝的实现：

int main()
{
	char str1[100] = "hello";
	char str2[] = "worldkgffijhgkjhgkjh";
	
	// 拷贝实现
	char *p1 = str1;
	char *p2 = str2;
	int n;
	scanf("%d", &n);
	while (n)
	{
		*(p1++) = *(p2++);
		n--;
	}

	
	puts(str1);
	return 0;
}