c语言求最长回文长度

1.源码实现

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

/*判断是不是回文*/
short ispalin(char *str, int n)
{
    int i = 0;

    for(i=0; i+i<n; i++)
    {
        if(str[i] != str[n-1-i])
        {
            return 0;
        }
    }

    return 1;
}

int maxsubpalin(char *a, char *b, int n)
{
    int m = 0;
    int u = 1;
    int v = 0;
    int i = 0;
    int j = 0;

    for(i=0; i<n; i++)
    {
        m = 1;

        for(j=n-i; j>0; j--)
        {
            if(ispalin(a+i, j))
            {
                m = j;

                if(m > u)
                {
                    u = m;
                    v = i;
                }

                break;
            }
        }
    }

    strncpy(b, a+v, u);

    b[u] = 0x00;

    return u;
}

int main()
{
    char str[1024];
    char c[1024];
    int n;

    memset(str, 0x00, sizeof(str));
    memset(c, 0x00, sizeof(c));

    while(scanf("%s", str) != EOF)
    {
        n = strlen(str);

        printf("%d\n", maxsubpalin(str, c, n));

        memset(str, 0x00, sizeof(str));
        memset(c, 0x00, sizeof(c));

    }

    return 0;
}

2.编译源码

$ gcc -o example examle.c -std=c89

4.运行及其结果

$ ./example
cabbade
4