Validation of scanf in c

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Validation of scanf in c

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#1 by (4 votes)

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I have a problem that I need to validate an entry to receive only integers, if I do not receive it, I should force the user to type an integer. I can not disregard numbers after the comma (in the case of decimals) and I can not return the entire equivalent of a letter (in case the user reports letter).

    int lerInteiro();

    int main()
    {
        int numero=0;
        numero=lerInteiro();
        printf("Numero: %i .\n",numero);
        return 0;
    }


   int lerInteiro()
   {
       int numero=0;
       int flag=0;
       do
       { 
            fflush(stdin);
            puts("Digite um numero inteiro: \n");

            if(scanf("%i",&numero)!=EOF)
            {
                flag=1;
                puts("Numero invalido!\n");
                puts("Digite apenas NUMEROS\n!");
                puts("Digite apenas numeros INTEIROS!\n");
            }
            else
            flag=0;
        }while(flag==1);    
    return numero;
   }

The program should stop when an integer is entered and return the number entered.

c scanf

asked by anonymous 25.10.2016 / 14:31

1 answer

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score 4 · Accepted Answer

Create a float variable and an integer to compare with each other in this way.

    #include<stdlib.h>
    #include<stdio.h>

    int lerInteiro();

    int main()
    {
        int numero=0;
        numero=lerInteiro();
        printf("Numero: %d .\n",numero);
        return 0;
    }


   int lerInteiro()
   {
       float numero=0;
       int flag=0;
       do
       { 
            fflush(stdin);
            puts("Digite um numero inteiro: \n");
            scanf("%f",&numero);
            int number = numero;
            if(number != numero)
            {
                flag=1;
                puts("Numero invalido!\n");
                puts("Digite apenas NUMEROS!\n");
                puts("Digite apenas numeros INTEIROS!\n");
            }
            else
            flag=0;
        }while(flag==1);    
    return numero;
   }