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  1. #include <stdio.h>
  2.  
  3. int main(int argc, char *argv[])
  4. {
  5. int option;
  6. int ch;
  7.  
  8. while(1) {
  9.  
  10.    if ( scanf("%d", &option) != 1) {
  11.       printf("Invalid input. Input must be a number between 1-4. Try again.\n");
  12.       while ( (ch=getchar())!=EOF && ch != '\n'); // Read out all the chars from input
  13.       continue;
  14.    }
  15.    else if (option<1 || option >4)  {
  16.       printf("Invalid input. Input must be a number between 1-4. Try again.\n");
  17.       continue;
  18.    }
  19.  
  20.    printf("option: %d\n", option);
  21.    // Valid input 
  22.    // Do whatever you want here with the 'option'
  23.  
  24.    break; //To break the infinite loop after reading a valid number
  25.    }
  26.  
  27. }
  28.  
Success #stdin #stdout 0s 2116KB
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stdin
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3
stdout
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option: 3
https://ideone.com/dmA5f5
language:
C (gcc 8.3)
created:
10 years ago
visibility:
public

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