C的fgets是否可以使用字符串*而不是来自文件？

编辑修复了Monte指出的错误(谢谢).疯狂地输入一个实用程序,同时相信至少有15个具有完全相同想法的其他人疯狂地做同样的事情并不会导致经过良好测试的代码.不好意思原始版本在后续调用中包含换行符.

char *sgets( char * str,int num,char **input )
{
    char *next = *input;
    int  numread = 0;

    while ( numread + 1 < num && *next ) {
        int isnewline = ( *next == 'n' );
        *str++ = *next++;
        numread++;
        // newline terminates the line but is included
        if ( isnewline )
            break;
    }

    if ( numread == 0 )
        return NULL;  // "eof"

    // must have hit the null terminator or end of line
    *str = '';  // null terminate this tring
    // set up input for next call
    *input = next;
    return str;
}


int main( int argc,char* argv[] )
{
    // quick and dirty test
    char *str = "abcndefghitjklksdnan12345n12345n123456nabcnn";
    char buf[5];

    while ( sgets( buf,sizeof( buf ),&str ))
        printf( "'%s'n",buf );
}