working with char arrays in C

Question

I'm writing a method that turns a decimal number into any radix (2-36) and prints the appropriate chars to the screen. The decimalToSymbol() method works correctly. The problem I'm having is in the while loop I assign ans[i] to a char and when I try to print it immediately after it is 0. I have looked online and found this is an OK way to assign the char but am not sure what is going wrong.

void writeRadixB(int decimalNumber, int radixB)
{
        char ans[80] = ""; 
        int i = 0;
        while(decimalNumber!= 0){ 
                printf("decNum: %d div by rB: %d equals %d\n", decimalNumber, radixB, decimalN
                printf("decNum: %d mod by rB: %d equals %d or char %c\n", decimalNumber, radix
                printf("i: %d\n", i); 
                decimalNumber = decimalNumber/radixB;
                ans[i] = decimalToSymbol(decimalNumber%radixB);
                printf("ans[%d] is %c\n", i, ans[i]);
                i++;
        }   
        printf("(%s) radix %d", ans, radixB);
}

Can you give an example of the values you're passing in? Also, shouldn't you be doing the modulus before you divide away the last digit each time? — FatalError
– FatalError, Commented Feb 1, 2012 at 20:52
I agree with FatalError and also want to note, that your digits will be ordered backwards in the string you create. — Nobody moving away from SE
– Nobody moving away from SE, Commented Feb 1, 2012 at 20:53
How do you know that the decimalToSymbol method works correctly? Also make sure to null terminate your string. `ans[i]='\0';1 before you print. — RussS
– RussS, Commented Feb 1, 2012 at 20:54
besides you should initialize char ans[80] = {0}; you should also check if (radixB != 0) return;. I'm not quite sure what purpose negative values would have here either. You should also add the (complete) output of your program to enhance the question... — moooeeeep
– moooeeeep, Commented Feb 1, 2012 at 21:07

Scott Hunter · Accepted Answer · 2012-02-01 20:54:54Z

1

You shouldn't change decimalNumber until AFTER you've extracted your digit. That, and your result is backwards.

answered Feb 1, 2012 at 20:54

Scott Hunter

50k12 gold badges64 silver badges107 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

asaelr · Accepted Answer · 2012-02-01 20:57:18Z

0

You should put the line ans[i] = decimalToSymbol(decimalNumber%radixB); before the line decimalNumber = decimalNumber/radixB;, (to not lose a digit). also, you probably want to reverse the string before printing it.

answered Feb 1, 2012 at 20:57

asaelr

5,4581 gold badge18 silver badges22 bronze badges

1 Comment

tubby Over a year ago

This was my problem, thank you. Just have to print the string backwards now

Collectives™ on Stack Overflow

working with char arrays in C

2 Answers 2

Comments

1 Comment

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Related