loop not working correctly

This is a discussion on loop not working correctly within the C Programming forums, part of the General Programming Boards category; i can't figure this out. the program loops but does not let you make another choice and just goes straight ...

  1. #1
    Registered User
    Join Date
    Nov 2012
    Posts
    2

    Question loop not working correctly

    i can't figure this out. the program loops but does not let you make another choice and just goes straight to press any button to continue,end. i'm new to all this so be gentile.
    Code:
    // Multi Function Calculator
    
    
    
    #include <stdio.h>
    #include <stdlib.h>
    #define Pi 3.14159
    int main(void)
    
    {
        
    
    char num,ans;
    float voltage, resistance , current, amps, miles, km;
    float r, A, in, ft;
    double F, C;
        
        do{
    
        printf("Please choose from following calculcations.\n");
        printf("Choose 1 to calculate Voltage.\n");
        printf("Choose 2 to calculate Current.\n");
        printf("Choose 3 to calculate Resistance.\n");
        printf("Choose 4 to calculate Miles to Kilometers.\n");
        printf("Choose 5 to calculate Kilometers to Miles.\n");
        printf("Choose 6 to calculate Fahrenheit to Celisus.\n");
        printf("Choose 7 to calculate Celisus to Fahrenheit.\n");
        printf("Choose 8 to calculate the Area of a Circle.\n");
        printf("Choose 9 to calculate Inches to Feet.\n");
        printf("Press enter to quit.\n");
    
    
        scanf("%c",&num);
        switch(num)
    
    {        
    
    case '1' : // Volatage 
            printf("Enter the current in amps =>");
            scanf("%f",&amps);
            printf("Enter the resistance in ohms =>");
            scanf("%f",&resistance);
            voltage = amps * resistance;
            printf("\nThe voltage is %0.2f volts.\n\n",voltage);
            break;
    
    case '2' : // Current
            printf("Enter the voltage in volts =>");
            scanf("%f",&voltage);
            printf("Enter the resistance in ohms =>");
            scanf("%f",&resistance);
            current = voltage / resistance;
            printf("\nThe current is %0.2f amps.\n\n",current);
            break;
    
    case '3' :  // Resistance
            printf("Enter the voltage in volts =>");
            scanf("%f",&voltage);
            printf("Enter the current in amps =>");
            scanf("%f",&amps);
            resistance = voltage / amps;
            printf("\nThe resistance is %0.2f ohms.\n\n",resistance);
            break;
    
    case '4' :  // Miles to KM
            printf("Enter number of miles =>");
            scanf("%f", &miles);
            km = miles*1.609334;
            printf("\n%.0f miles is %.2f kilometers.\n\n", miles, km);
                break;
    
    case '5' :  // KM to Miles
            printf("Enter number of kilometers =>");
            scanf("%f", &km);
            miles = km*0.6214;
            printf("\n%.0f kilometers is %.2f miless.\n\n", km, miles);
                break;
    
    case '6' :  // F* to C*
            printf("Enter degrees Fahrenheit =>", F);
            scanf("%lf", &F);
            C = (F-32)*5/9;
            printf("\n%.0lf degrees Farenheit is %.2lf degrees Celsius.\n\n", F, C);
            break;
    
    case '7' :  // C* to F*
            printf("Enter degrees Celsius =>", C);
            scanf("%lf", &C);
            F = (C*(9/5))+32;
            printf("\n%.0lf degrees Celsius is %.2lf degrees Farenheit.\n\n", C, F);
            break;
    
    case '8' :  //Area of circle
            printf("Enter radius of the circle =>", r);
            scanf("%f", &r);
            A = Pi*r*r;
            printf("\nThe area of the circle is %.2f.\n\n", A);
            break;
    
    case '9' : // Inches to feet
            printf("Enter number of inches =>", in);
            scanf("%f", &in);
            ft = in/12;
            printf("\n%.0f inches is %.2f feet.\n\n", in, ft);
            break;
    
         
            default : exit(0);
        
        }
        
        {
                
                printf("Do you want another calculation?(Y/N)=>",ans);
                scanf(" %c",&ans);
                printf("\n");printf("\n");
                system("cls");
    }
            } while (ans == 'y');
    
    return(0) ;
    
    }

  2. #2
    Registered User
    Join Date
    May 2009
    Posts
    2,577
    This is really the only line of your code; I looked twice at.
    Code:
    scanf("%c",&num);
    It is normal for beginnings to forgot about the newline/linefeed char.

    Adding a space before the "%" percent sign skips over white-space chars like newlines.

    As like this.
    Code:
    scanf(" %c",&num);
    Tim S.
    "Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the universe trying to produce bigger and better idiots. So far, the Universe is winning." Rick Cook

  3. #3
    Registered User
    Join Date
    Nov 2012
    Posts
    2
    awesome, thanks. i've written this out 3 times and was going crazy. now i can sleep at nite.

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