CODEWITHSUNDEEP
c
YoTengoUnLCD
YoTengoUnLCD

Reputation: 598

Why is this program giving me an infinite loop? Simple program

I was trying to make a simple program to change the base of a number (i,e I give the bases 2 and 5, and the number 101 and I should get 10) and when doing the function to read the bases I get the following: If I type in correctly the data it works, if I don't (for example, I type "231") the program goes into an infinite loop, why is this happening?

#include <stdio.h>

int main(void)
{
    int base1,base2;
    readBases(&base1,&base2);
    printf("%d%d\n",base1,base2);
    return 0;
}

void readBases(int *baseOrig, int * baseDest)
{
    int aux1,aux2,flag;
    do
    {
        printf("Type in the bases, in the format <a>b:");
        flag=scanf("<%d>%d",&aux1,&aux2);
        if(aux1<2||aux1>10||aux2<2||aux2>10)
        {
            flag=0;
            printf("Invalid data.\n");
        }
    }while(flag!=2);
    *baseOrig=aux1;
    *baseDest=aux2;
}

Upvotes: 0

Views: 72

Answers (1)

mksteve
mksteve

Reputation: 13073

 flag=scanf("<%d>%d",&aux1,&aux2);

reads as much of the input stream as it can, and returns the number of converted fields.

If it can't read anything, then it will not progress input - getting stopped. You need some way of reading the data - safely.

Line termination works quite well.

  while( fgets( buffer, sizeof( buffer), stdin ) != NULL ){
       flag = sscanf( buffer, "<%d>%d",&aux1,&aux2);

  }

Upvotes: 1

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