是否可以在 scanf 或 sscanf 中使用 strcpy？ （C语言）

Question

I read somewhere that when we use structs we can't just write something like « example1.name = "Jim"; », instead of it we should write « strcpy(example1.name, "Jim"); »

The thing is that I need to use a struct and I need to scanf (and right after that sscanf) some information that corresponds to a string and I don't know how I should do it.

Could somebody help me, please?

Edit:

My code isn't complete and I know it's wrong, but I'll post it here so that you know what I am talking about:

int main(){

    struct Cards{
        int value;
        char type[4];
    };

    for(i=1, 0 < i && i < 11, i++){  
         struct Cards cardi;
    }

    scanf("%d %s", &cardi.value, cardi.type); 
/*at this point I just know it's wrong but I am really bugged.
  I thought about something like «scanf("%d %s", &cardi.value, strcpy(cardi.type, "%s"));»
  but I just know it's very wrong */ 


    return 0;
}

Answer 1

This isn't true only about structs, but for all strings. You can use = for strings, only when you initialize them. You can scanf a string and place it in a string. Example:

scanf("%s", my_struct.str);

If you already have a string and you want to pass it in a struct, or in an other string variable you then need strcpy:

char str1[] = "abc", str2[4];
strcpy(str2, str1);

or

strcpy(my_struct.str, str1);

Edit:

for(i=1, 0 < i && i < 11, i++) {
    struct Cards cardi;
}

In your code cardi is not card0, card1 etc, it is a struct Cards variable with the name cardi.

If you want to store 10 cards, you sould make an array of struct Cards with capacity of 10 like:

struct Cards array[10];
for (i = 0; i < 10; i++) {
    scanf("%d %s", &array[i].value, array[i].type);
}

Anyway i suggest that you focus on learning the basics on arrays, strings and pointers before you use structs.

Edit 2: You don't want to define structs inside your main, because in that way, if you write a function it will not "see" your struct. Structs usually are written in the top of the code.

Answer 2

Your use of scanf() is correct. However scanning strings using %s is dangerous and discouraged. This is because the type member of your structure has space for only 4 characters, including the terminating '\\0' (NUL) character. Entering a string longer than 3 characters will result in the extra characters being written into an unknown area of memory likely corrupting other variables and leading to incorrect program execution or a program crash. You can correct this by adding a string length limit, simply replace %s with %3s , where 3 is the maximum numbers of characters that will be accepted ( scanf will automatically add a '\\0' (NUL) character following the last scanned character).

Below are some additional comments:

If you want to declare an array for 10 Cards, you could do it this way without any loops:

    struct Cards cardi[10];

To scan values into the first card (C arrays are 0-based):

    // this will scan into the first card; type field is restricted to at most 3 characters
    scanf("%d %3s", &cardi[0].value, cardi[0].type); 

At the top of the file you'll want to add:

#include <stdio.h>

This header file provides a prototype (declaration) for the scanf function (among many others).