【c语言】结构体改错题

#include <stdio.h>
#include <string.h>
struct sample
{
    int a, b;
    char*ch;
};
void fl(struct sample p)
{
    p.a += p.b;
    p.ch[2] = 'x';
    printf("%d,", p.a);
    printf("%s\n", p.ch);
}
int main()
{
    struct sample samp;
    samp.a = 1000;
    samp.b = 100;
    strcpy(samp.ch, "abcd");
    fl(samp);
    return 0;
}

报错：samp未初始化。

修改见注释，供参考：

#include <stdio.h>
#include <string.h>
#include <malloc.h>
struct sample
{
    int a, b;
    char*ch;
};
void fl(struct sample p)
{
    p.a += p.b;
    p.ch[2] = 'x';
    printf("%d,", p.a);
    printf("%s\n", p.ch);
}
int main()
{
    struct sample samp;
    samp.a = 1000;
    samp.b = 100;
    samp.ch = (char*)malloc(32);//修改 ，需要给*ch申请一块空间
    strcpy(samp.ch, "abcd");
    fl(samp);
    return 0;
}