Topic link ：

Code shoe set (matiji.net)

Their thinking ：

For non character data, we have %nd   %m.nf

For strings, we also have their width and precision ,

• namely %m.ns

Among them m It represents the width , That is, how many columns

n Then the first few digits of the string are used

• Be careful ：

%m.ns To work with %m.nf（ there n It means precision ）  Make a distinction

It's easy to get wrong ：

because scanf When a function encounters a space when entering , It will automatically stop reading data after spaces

• So an examination site of this topic ：

How to read a whole line of string in a string containing spaces ？

have access to gets ( ) function （ This function is only used to read strings ）,

This function ends the reading with the Enter key , Therefore, the input will not be terminated when encountering spaces

• But this function has a disadvantage ：

When receiving the input of string ,

It does not check the array subscript ,

So if the input character length exceeds the maximum space that the character array can hold , No errors at compile time ,

But when running, the array will be out of bounds , Or memory leaks

• And to solve these problems ,

C++ There's one in it cin.getline ( ) function , It limits the length of the character array in which the string is stored  

Reference code ：

#include<bits/stdc++.h> 

using namespace std;

int main( )
{
    char arr[6] = {'0'};
    /* string  The type is not C The built-in type of language , So it can't be used for  printf  function */
    //scanf("%6s",arr); Stop reading when encountering spaces 

    gets(arr);
    printf("%6.3s",arr);
    return 0;
}