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Rami Raghfan
Rami Raghfan

Reputation: 163

How to make a C program loop back to reprompt for new input?

For example, to this program that calculates equations of grade 3, after it calculates the equation, it stops. how do I make it so it loops back again to the start without executing again? I'm still new to this platform so I'll be in your care! 

#include < stdio.h >

int main() {
  int a, v, b, c, delt;
  float x1, x2;

  printf("\nIntroduceti cele 3 parametrii ecuatia: ");

  scanf("%d %d %d", & a, & b, & c);
  if (a != 0) {
    v = pow(b, 2);
    delt = v - (4 * a * c);

    if (delt >= 0) {

      delt = sqrt(delt);
      x1 = -(b + delt) / (2.0 * a);
      x2 = -(b - delt) / (2.0 * a);

      printf("\nValoara lui x1 este: %f", x1);
      printf("\n");
      printf("\nValoara lui x2 este: %f", x2);

    } else {
      printf("Ecuatia nu are soluti! \n");
    }

  } else if (a == 0) {
    printf("\nBLACKHOLE");
  }

  return 0;
}

Upvotes: 0

Views: 1105

Answers (2)

DLM
DLM

Reputation: 565

You could wrap everything in a do-while loop and ask the user whether he wants to continue the execution or not, for example:

int a,v,b,c,delt;
float x1,x2;
char choice;
do{
    printf("\nIntroduceti cele 3 parametrii ecuatia: ");
    scanf("%d %d %d", &a, &b, &c);
    if(a!=0)
    {
        v=pow(b, 2);
        delt = v-(4*a*c);

        if (delt>=0)
        {
            delt=sqrt(delt);
            x1=-(b+delt)/(2.0*a);
            x2=-(b-delt)/(2.0*a);

            printf("\nValoara lui x1 este: %f", x1);
            printf("\n");
            printf("\nValoara lui x2 este: %f", x2);
        }
        else
        {
            printf("Ecuatia nu are soluti! \n");
        }
    }
    else if(a==0)
    {
        printf("\nBLACKHOLE");
    }
    printf("\nEvaluate new equation?(y/n) ")
    scanf("%c",&choice)
}while(strcmp(choice,"y")==0);

return 0;

The block inside the do{...} will execute at least once, then the user will be asked to input a char (y/n) to decide whether to continue or not. The strcmp(string1,string2) compares two strings and returns 0 if they are equal, so if the user chose "y", the strcmp will return 0 and the do-while will be executed again.

Upvotes: 1

terales
terales

Reputation: 3200

Just wrap your code into an infinite loop (while(1) { /* Your code here*/ }):

#include < stdio.h >

int main() {
  int a, v, b, c, delt;
  float x1, x2;

  while (1) {
    printf("\nIntroduceti cele 3 parametrii ecuatia: ");

    scanf("%d %d %d", & a, & b, & c);
    if (a != 0) {
      v = pow(b, 2);
      delt = v - (4 * a * c);

      if (delt >= 0) {

        delt = sqrt(delt);
        x1 = -(b + delt) / (2.0 * a);
        x2 = -(b - delt) / (2.0 * a);

        printf("\nValoara lui x1 este: %f", x1);
        printf("\n");
        printf("\nValoara lui x2 este: %f", x2);

      } else {
        printf("Ecuatia nu are soluti! \n");
      }

    } else if (a == 0) {
      printf("\nBLACKHOLE");
    }
  }

  return 0;
}

Upvotes: 0

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