我认为我的视觉工作室版本有问题，一些操作员发生了变化，因为我从 2016 年的书中复制了代码

Question

#include <stdio.h>
#include <string.h>
 #define SIZE 20

 
 int main(void)
 {
     char string1[SIZE];
    
     char string2[] = "string literal"; 
    
     size_t i; 
    
         
     printf("%s", "Enter a string (no longer than 19 characters): ");\\problem there
    
     scanf_s("%19s", string1); \\problem there
     
     printf("string1 is: %s\n",string1)
     
     printf("string2 is: %s\n","string1 with spaces between characters is:\n", string2);

  for (i = 0; i < SIZE && string1[i] != '\0'; ++i) {
     printf("%c ", string1[i]);
     } 
 

puts(""); }

\ i think promblem in version of my visual studio, some operator have change, because code i copy from book 2016

Answer 1

The call of scanf_s with the conversion specifier s requires one more argument. That is instead of

scanf_s("%19s", string1); \\problem there

you need to write

scanf_s("%19s", string1, ( rsize_t )20 );

From the C Standard (K.3.5.3.2 The fscanf_s function). The quote is valid for the function scanf_s .

4 The fscanf_s function is equivalent to fscanf except that the c, s, and [ conversion specifiers apply to a pair of arguments (unless assignment suppression is indicated by a *). The first of these arguments is the same as for fscanf. That argument is immediately followed in the argument list by the second argument, which has type rsize_t and gives the number of elements in the array pointed to by the first argument of the pair. If the first argument points to a scalar object, it is considered to be an array of one element.

Though it would be better to write (if you allow the user to enter embedded spaces in the string)

scanf("%19[^\n]", string1);

or simply

scanf("%19s", string1);

In this call of printf

printf("string2 is: %s\n","string1 with spaces between characters is:\n", string2);

there is only one conversion specifier s but two arguments. The argument string2 is not used.

It seems you mean the following

printf("string2 is: %s\n", string2);
printf( "string1 with spaces between characters is:\n" );

In the condition of this for loop

for (i = 0; i < SIZE && string1[i] != '\0'; ++i) {

the expression i < SIZE is redundant.