leetcode最长前缀，编译错误，求解答

代码如下:

char * longestCommonPrefix(char ** strs, int strsSize){

    char *c = (char *)malloc(sizeof(char)*128);

    int j = 0;

    int k = 0;

    while(strs[0][j]){

    char s = strs[0][j];

    for(int i = 1; i < strsSize; i++)

    {

        if(strs[i][j] != s)

            {if(k == 0)

                return "";

            c[k] = 0;

            return c;

            }

    }

    c[k++] = s;

    j++;

    }

}

显示错误:

solution.c: In function 'longestCommonPrefix'

Line 20: Char 1: error: control reaches end of non-void function [-Werror=return-type]

 }

 ^

cc1: some warnings being treated as errors