如何使用scanf进行char数组输入？

Question

I set a char array of size of 10 and want to check the real size of the input permitted.

I tested

123456789; 1234567890; 123456789123456789

Interestingly, all of them passed and got the right output which are

123456789; 1234567890; 123456789123456789

It confused me a lot because I thought the last two are wrong input.

Does that make sense or is it a compiler difference?

This is the code

#include <stdio.h>
main()    
{    
char input[10];    
scanf("%s", input);    
printf(input);    
}  '  

Answer 1

The scanf() with format specifier %s scans the input until a space is encountered. In your case, what you are seeing is undefined behavior. Your array can hold 10 char s, but you are writing out of its boundaries.

While you are getting an expected answer now, this is not always guarnateed and may instead cause a crash.

It is advisable to use a function such as fgets() takes care of buffer overflow.

Answer 2

您可以使用

scanf("%9s", input);