VS Code. File contents are not displayed in TERMINAL and OUTPUT

Question

I'm using VSCode on Ubuntu 24.04.01.The screenshot shows a program that reads and displays the contents of a file. The "my_file.txt" contains the word "Hello". When I run the code on the TERMINAL and OUTPUT there is no "Hello" message. How can I print the word "Hello" on the TERMINAL and OUTPUT? Thanks for the answer

#include<stdio.h>

int main()
{
   
    char buff[100];
  
   FILE *in = fopen("my_file.txt", "r");
    if(in == NULL)
       return 2;

    char ch;
    int i = 0;
    while(ch = fgetc(in) != EOF)
       buff[i++] = ch;
    buff[i] = '\0';
  
    puts(buff);  
        
    fclose(in);
    
    return 0;
}

I tried searching in the settings and in the file task.json...

Answer 1

There are at least three drawbacks in your program.

The first one is that the variable ch should be declared as having type int. Otherwise the result of such a condition like ch == EOF or ch != EOF is implementation defined.

The second drawback is that the condition in this while loop

while(ch = fgetc(in) != EOF)

is equivalent to

while( ch = ( fgetc(in) != EOF ) )

due to the operator precedence and as a result the variable ch will be set either to 1 or 0.

You need to write at least like

while (  ( ch = fgetc( in ) ) != EOF )

And the third drawback is that you should guarantee that the array buff will not be overwritten. So you need to write for example

#include <stdio.h>

int main( void )
{
    enum { N = 100 };
    char buff[N];
  
    FILE *in = fopen( "my_file.txt", "r" );
    
    if ( in == NULL ) return 2;

    int ch;
    int i = 0;
  
    while ( i < N - 1 && ( ch = fgetc( in ) ) != EOF )
    {
        buff[i++] = ch;
    }

    buff[i] = '\0';
  
    puts( buff );  
        
    fclose( in );
    
    return 0;
}

Also you should be sure that the file indeed exists in the working directory. You could write for example

if ( in == NULL ) 
{
    puts( "File not found." );
    return 2;
}