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I keep getting values ​​as long as the user does not enter a positive integer(and i control if user entered negative values or if user entered an integer). I try to do it without using isdigit, it enters an infinite loop when I enter a character. /@Weather Vane solved my problem,thanks everybody/

int quantity;
        
        printf("Please enter term(s) number");
        scanf("%d",&quantity);
        while( 1){
            if(quantity<0){
                printf("Please enter “positive”  number");
                scanf("%d",&quantity);
            }
        
            if(!(quantity>='0' && quantity<='9')){
                printf("Please enter “a”  number");
                scanf("%d",&quantity);
            }
        }
user15465584
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    `while( 1)` is an infinite loop. How to exit it? – Paul Ogilvie Mar 25 '21 at 15:14
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    You read an integer. Then `quantity>='0'` will always be false (`'0'` means ASCII character 0) – Paul Ogilvie Mar 25 '21 at 15:15
  • You should add a `break` statement where you are supposed to exit the loop. – Roberto Caboni Mar 25 '21 at 15:15
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    The 'character' is presumably non-numeric. This blocks the input until you remove it. One easier way to deal with this to use `fgets()` for all input and then `sscanf()` and then, if `sscanf()` returns the wrong value, or the entry is the wrong value, you dump the string and ask for another.. – Weather Vane Mar 25 '21 at 15:20
  • @PaulOgilvie while( ( !(quantity>='0' && quantity<='9')) || quantity<0) when i use this and enter a character there is still infinite loop,ı dont know how to solve it – user15465584 Mar 25 '21 at 15:26
  • @RobertoCaboni If user provides a positive integer (not a character or a negative integer) I want to exit and I typed this way which part should I edit – user15465584 Mar 25 '21 at 15:30
  • @WeatherVane honestly i don't use anything but scanf because homework – user15465584 Mar 25 '21 at 15:31
  • Please see [How to clear input buffer in C?](https://stackoverflow.com/questions/7898215/how-to-clear-input-buffer-in-c) Particularly [this answer](https://stackoverflow.com/a/26081123/4142924). That means you will use `getchar()` but you can find a way to do it with `scanf()` too. – Weather Vane Mar 25 '21 at 15:36
  • @WeatherVane Thank you very much, that was the problem, solved.if you can type this an answer i can approve it,i dont know another way to close the session*/ – user15465584 Mar 25 '21 at 15:51

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