Q:

scanf is omitted in do while loop

I have this program and during its first loop it works as intended, but from the 2nd loop on it doesn't execute the first scanf. We haven't been taught pointers, so I don't know if they can solve the problem. Should I try the problem with another loop syntax like for? Any help is appreciated.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char *argv[])
{
    char type[20];
    int amount;
    double price;
    double priceP;
    double priceG;
    double priceA;
    double pricePL;
    double priceC;
    price=0;
    char frouro[4]= "add";
    char payment[5];
    double refund;

    do{

       printf("What kind of material do you want to recycle today?. It has to be either paper , glass, aluminium, plastic or cloth\n");

       scanf(" %s" , &type);

       printf("how many materials do you want to recycle today? It has to be more than 1 and a maximum of 10\n");

       scanf(" %d" , &amount);

       if (strcmp(type, "paper") == 0)
          { 

           priceP = priceP + amount * 0.10;

          }   
       if (strcmp(type, "glass") == 0)
          { 

           priceG =priceP + amount * 0.20;

          }
       if (strcmp(type, "aluminium") == 0)
          { 

          priceA =  priceA + amount * 0.15;

          }
       if (strcmp(type, "plastic") == 0)
          { 

          pricePL =  pricePL +amount * 0.05;

          }  
       if (strcmp(type, "cloth") == 0)
          {

           priceC =  priceC + amount * 0.50;

          }  
      printf("do you want to do anything else?\n");

      scanf(" %c", &frouro);
      }while(strcmp(frouro,"add")==0 && strcmp(frouro,"end")!=0);

      return 0;
}

A:

Change scanf(" %c", &frouro); to scanf("%s", &frouro);.
As you are storing 1 char, during while conditional check it will be always false.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char *argv[])
{
    char type[20];
    int amount;
    double price;
    double priceP;
    double priceG;
    double priceA;
    double pricePL;
    double priceC;
    price=0;
    char frouro[4]= "add";
    char payment[5];
    double refund;

    do{

       printf("What kind of material do you want to recycle today?. It has to be either paper , glass, aluminium, plastic or cloth\n");

       scanf(" %s" , &type);

       printf("how many materials do you want to recycle today? It has to be more than 1 and a maximum of 10\n");

       scanf(" %d" , &amount);

       if (strcmp(type, "paper") == 0)
          { 

           priceP = priceP + amount * 0.10;

          }   
       if (strcmp(type, "glass") == 0)
          { 

           priceG =priceP + amount * 0.20;

          }
       if (strcmp(type, "aluminium") == 0)
          { 

          priceA =  priceA + amount * 0.15;

          }
       if (strcmp(type, "plastic") == 0)
          { 

          pricePL =  pricePL +amount * 0.05;

          }  
       if (strcmp(type, "cloth") == 0)
          {

           priceC =  priceC + amount * 0.50;

          }  
      printf("do you want to do anything else?\n");

      scanf("%s", &frouro);
      }while(strcmp(frouro,"add")==0 && strcmp(frouro,"end")!=0);

      return 0;
}

