Automating user input for C program

Question

I am planing to make a C program using array of structures which takes input as strings i.e., name of movie and genre(4 different genres):

struct movie
   {
      char name[30];
      char genre[4][10];
   }m[30];

void main()
{
   int i,j;
   for(i=0;i<30;++i)
   {
      scanf("%s",m[i].name);                     //Removing gets
      for(j=0;j<4;++j)
      {
          scanf("%s",m[i].genre[j]);             //Removing gets
      }
   }
}

I want to automate the user input of the program from a pre-defined source e.g a text file, so that I don't have to insert all the input manually. Is there a script(python/bash) to do this or any other method that can make my job easier for 100s of input.

The reason behind using the C program is to store the inputs in a file for future use.

Since your program is just reading from standard input, you can use the file redirection or pipeline features of the shell to feed it input. — Ian Abbott
– Ian Abbott, Commented Apr 24, 2018 at 15:18
On a Unix/Linux system, use input redirection, as in abelenky's answer. (Dunno how easy/convenient this would be under Windows, though.) While you're at it, create a test input file with name and genre strings longer than expected, and watch your program explode as the obsolete gets function fails to notice the overflow, and clobbers adjacent parts of memory. — Steve Summit
– Steve Summit, Commented Apr 24, 2018 at 15:19
@glennjackman gets has no way to prevent buffer overrun. For that reason, it has been removed from C11. — Ian Abbott
– Ian Abbott, Commented Apr 24, 2018 at 15:25
@glennjackman Do a google search on "gets unsafe". You'll get plenty of answers. — Steve Summit
– Steve Summit, Commented Apr 24, 2018 at 15:29

abelenky · Accepted Answer · 2018-04-24 15:17:25Z

7

Write it to accept input from the keyboard. Then use input redirection:

myprogram.out < SampleTestData.txt

Uses the SampleTestData.txt file as if it were keyboard input.

answered Apr 24, 2018 at 15:17

abelenky

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2 Comments

Vivek Biswas Over a year ago

i am using gcc on linux, so should my steps be like this : 1st step: gcc myprogram.c 2nd step: SampleTestData.txt > ./a.out

runwuf Over a year ago

you might want to read on unix redirection: link ./a.out < SampleTestData.txt

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