C语言字符串总结

常见字符串操作，先列这几个吧。

#include<stdio.h>
#include<string.h>
#include<ctype.h>
//删除字符串中指定字符
char * DeleteChar(char *s, char c)//c为要删除字符
{
	int i, j = 0;
	for ( i = 0; *(s + i) != '\0'; i++)
	{
		if (*(s + i) != c)
		{
			*(s + j) = *(s + i);
			j++;
		}
	}
	*(s + j) = '\0';
	return s;
}

//求字符串长度
int str_length(const char *s)
{
	int count = 0;
	while (*s++ != '\0')
	{
		count++;
	}
	return count;
}


//字符串大小写转换
void Tolower(char *s)
{
	
	for (int i = 0; *(s + i) != '\0'; i++)
	{
		if (*(s + i) >= 65 && *(s + i) <= 90)
		{
			*(s + i) = *(s + i) + 32;
		}
	}
		
}

//字符串连接
char * str_cat(char *s1, const char *s2)
{
	char *temp = s1;
	while (*s1 != '\0')
	{
		s1++;
	};
	while (*s2 != '\0')
	{
		*s1++ = *s2++;
	}
	*s1 = '\0';
	return temp;

}


//字符串复制		
char * str_cpy(char *s1, char *s2)
{
	char *temp = s1;
	while (*s2 != '\0')
	{
		*s1++ = *s2++;
	}
	*s1 = '\0';
	return temp;
}


int main(void)
{
	char s[20] = "hefahifAZfpiwf";

	//字符串长度
	printf("字符串长度为%d\n", str_length(s));

	//删除字符串中'h'字符
	DeleteChar(s, 'h');
	printf("%s\n", s);

	//转换为小写字符
	Tolower(s);
	printf("转换为小写字母:%s\n", s);

	//连接两个字符
	char s1[30] = "haha";
	char s2[10] = "ffafhi";
	str_cat(s1, s2);
	printf("将s2连接到s1后：%s\n", s1);

	char s3[10] = "zhaf";
	char s4[10] = "fah";
	str_cpy(s3, s4);
	printf("将s4复制到s3后：%s\n", s3);
}

C语言自带的字符串处理函数

1.strlen，求字符串长度

size_t strlen(const char *s)
{
	size_t len = 0;
	while (*s++)
		len++;
	return len;
}

不包括null字符在内的字符串长度

2.strcpy，字符串复制

char *strcpy(char *s1, const char *s2)
{
	char *temp = s1;
	while (*s1++ = *s2++);
	return temp;
}