Float doesn't seem to be working?

[SoLDMG]

Hello everyone, I have a few problems with float not working like I think it should...? Using TCC to compile.

Basically, I'm trying to implement functions to calculate radians, degrees and powers.

#include <stdio.h>
#define PI 3.14159265

int main(void){
    double rads = myrad(90);        // Should be 1.570796
    double degs = mydeg(rads); // Should be 90.000000
    double pows = mypow(2, 4);        // Should be 16.000000
    
    printf("90 degrees to radians = %lf\n", rads);
    printf("1.570796 radians to degrees = %lf\n", degs);
    printf("2^4 = %lf\n", pows);
    return 0;
}

int mypow(double x, double y){
    double i = 0;
    double power = 1;
    while(i < y){
        power *= x;
        i++;
    }
    return power;
}

int myrad(double x){
    double radians = x * PI / 180;
    return radians;
}

int mydeg(double x){
    double degrees = x / PI * 180;
    return degrees;
}

The output is:

90 degrees to radians = 0.000000
1.570796 radians to degrees = 0.000000
2^4 = 0.000000

I can't change the "int"s to "double"s because TCC throws a

main.c:*insert_line*: error: incompatible types for redefinition of '*insert_function*'

at me.
Can anyone please help me with this, as I'm trying to teach myself with some books.

[Salem]

You should prototype all your functions before you use them.
Otherwise, the compiler automatically creates a declaration for them - based on the first use, which it then finds is incompatible with the later actual definition.

Put these 3 lines above main.

int mypow(double x, double y);
int myrad(double x);
int mydeg(double x);

[mad-hatter]

Try:

#include <stdio.h>
#define PI 3.14159265

double mypow(double x, double y){
    double i = 0;
    double power = 1;
    while(i < y){
        power *= x;
        i++;
    }
    return power;
}
 
double myrad(double x){
    double radians = x * PI / 180;
    return radians;
}
 
double mydeg(double x){
    double degrees = x / PI * 180;
    return degrees;
}

int main(void){
    double rads = myrad(90);        // Should be 1.570796
    double degs = mydeg(rads);      // Should be 90.000000
    double pows = mypow(2, 4);      // Should be 16.000000
     
    printf("90 degrees to radians = %lf\n", rads);
    printf("1.570796 radians to degrees = %lf\n", degs);
    printf("2^4 = %lf\n", pows);
    return 0;
}

C:\Users\Michael\Desktop\test>g++ test.c -o test.exe

C:\Users\Michael\Desktop\test>test
90 degrees to radians = 1.570796
1.570796 radians to degrees = 90.000000
2^4 = 16.000000

[Tien Nguyen]

Yeah.  I would put the functions first instead of after the main.  That way you don't need the prototype to specifically preface it.  It looks like it is fine from inspection except put all your functions before the main.  The prototype is supposed to explicitly make it clear to the compiler what to expect but in my two years of hardcore tcc programming it should only be used if you are going to be calling an external function like an assembly language module, etc.

[rstanley]

Yeah. ..I would put the functions first instead of after the main. ..That way you don't need the prototype to specifically preface it. ..It looks like it is fine from inspection except put all your functions before the main. ..The prototype is supposed to explicitly make it clear to the compiler what to expect but in my two years of hardcore tcc programming it should only be used if you are going to be calling an external function like an assembly language module, etc.

Actually prototypes should be used in all programs for many reasons.

1) If you define the functions above main() without prototypes, you could easily get into a "Chicken and the Egg" syndrome, where function A may call function B, and function B might call function A. In what order would you define them??? Either order would not work!!

2) In the real world, many if not most programs might start out as a one file program, but then expand into a multi-source file application with possibly multiple header files. It would be easier to expand the program if you have prototypes in place from the start.

3+) I'm sure there are many more reasons, but with only one cup of coffee in me, I will stop here!

@SoLDMG:

You should think about moving to a more modern compiler for Windows. Turbo C is non-standard, and too old to be able to use C99 and C11 C Programming Language Standards. Turbo C 1.0 is completely useless, and should be thrown away!

This code will NOT execute correctly in TC 1.0!!! Not sure if or when they corrected this bug!

int main(void)
{
   float value = -123.45;

   printf("value == %.2f\n", -value);

   return 0;
}

[SoLDMG]

With TCC I meant Tiny C Compiler, haha. My bad. Thank you for the code though.

[mad-hatter]

OK, point taken.

#include <stdio.h>
#define PI 3.14159265

double mypow(double x, double y);
double myrad(double x);
double mydeg(double x);

int main(void){
    double rads = myrad(90);        // Should be 1.570796
    double degs = mydeg(rads);      // Should be 90.000000
    double pows = mypow(2, 4);      // Should be 16.000000
     
    printf("90 degrees to radians = %lf\n", rads);
    printf("%lf radians to degrees = %lf\n", rads, degs);
    printf("2^4 = %lf\n", pows);
    return 0;
}

double mypow(double x, double y){
    double i = 0;
    double power = 1;
    while(i < y){
        power *= x;
        i++;
    }
    return power;
}
 
double myrad(double x){
    double radians = x * PI / 180;
    return radians;
}
 
double mydeg(double x){
    double degrees = x / PI * 180;
    return degrees;
}

[CodeSlapper]

I think using const double PI = 3.14159265 is better than using a macro.

One benefit I like is being able to see the value of the variable when you are debugging.