一维字符型数组算法整理

1. 字符串得倒置

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

int main(void)
{
    char str[32] = {0};
    int len = 0;
    int i = 0;
    char tmp = 0;

    gets(str);
    len = strlen(str);
    
    for (i = 0; i < len/2; i++)
    {
        tmp = str[len-1-i];
        str[len-1-i] = str[i];
        str[i] = tmp;
    }

    puts(str);

    return 0;
}

2. strlen函数功能的实现

#include <stdio.h>

int main(void)
{
	char str[256] = {0};
	int cnt = 0;
	int i = 0;

	gets(str);

	while (str[i] != '\0')
	{
		cnt++;
		i++;
	}

	printf("cnt = %d\n", cnt);

	return 0;
}

3. strcpy函数功能的实现

#include <stdio.h>

int main(void)
{
	char src[256] = {0};
	char dst[256] = {0};
	int i = 0;

	gets(src);
	
	while (src[i] != '\0')
	{
		dst[i] = src[i];
		i++;
	}

	dst[i] = '\0';

	printf("dst = %s\n", dst);

	return 0;
}

4. strcmp函数功能的实现

#include <stdio.h>

int main(void)
{
    char str1[256] = {0};
    char str2[256] = {0};
    int i = 0;

    gets(str1);
    gets(str2);

    while (str1[i] == str2[i] && '\0' != str1[i])
    {
        i++;
    }

    printf("%d\n", str1[i] - str2[i]);

    return 0;
}

5. strcat函数功能的实现

#include <stdio.h>

int main(void)
{
	char str1[256] = {0};
	char str2[256] = {0};
	int i = 0;
	int j = 0;

	gets(str1);
	gets(str2);

	while (str1[i] != '\0')
	{
		i++;
	}

	while (str2[j] != '\0')
	{
		str1[i] = str2[j];
		i++;
		j++;
	}

	str1[i] = '\0';

	printf("%s\n", str1);

	return 0;
}