Values are not calculating?

**Dobblaar** · 11-29-2013

Finally got a programme partially working, could anyone advise why the values are not showing? Is this down to incorrect formula or i havent declared the values etc?

Code:

#include <stdio.h>
#include <math.h>

float timeconstant(float R, float C);

float R;
float C;
float time_c;
double const V1 = 0.35;
double const V2 = 0.75;
double const V3 = 0.95;
float cap_c_formula;
float cap_charge1(float R1, float C1, int V1);
float cap_charge2(float R1, float C1, int V2);
float cap_charge3(float R1, float C1, int V3);

int main(void)
{

printf("State a Value For The Resistor?\n");
scanf("%f",&R);
printf("State a Value For The Capacitor?\n");
scanf("%f",&C);
time_c = timeconstant(R,C);
printf("Time to Charge the Capacitor to 35 Percent : %f \n" ,cap_charge1);
printf("Time to Charge the Capacitor to 75 Percent : %f \n" ,cap_charge2);
printf("Time to Charge the Capacitor to 95 Percent : %f \n" ,cap_charge3);

getchar();
getchar();

}
float timeconstant(float R1, float C1)
{
float t_constant;
t_constant = R1*C1;
return t_constant;
}
float cap_charge1(float R1, float C1, int V1)
{
    float capc_charge1;
    capc_charge1 = -(R1*C1)*log(V1);
}
float cap_charge2(float R1, float C1, int V2)
{
    float capc_charge2;
    capc_charge2 = -(R1*C1)*log(V2);
}
float cap_charge3(float R1, float C1, int V3)
{
    float capc_charge3;
    capc_charge3 = -(R1*C1)*log(V3);
}

**std10093** · 11-29-2013

You compiled it and got nothing??

Here's what I got (by enabling -Wall flag)

Code:

px.c: In function ‘main’:
px.c:25:1: warning: format ‘%f’ expects argument of type ‘double’, but argument 2 has type ‘float (*)(float,  float,  int)’ [-Wformat]
px.c:26:1: warning: format ‘%f’ expects argument of type ‘double’, but argument 2 has type ‘float (*)(float,  float,  int)’ [-Wformat]
px.c:27:1: warning: format ‘%f’ expects argument of type ‘double’, but argument 2 has type ‘float (*)(float,  float,  int)’ [-Wformat]
px.c: In function ‘cap_charge1’:
px.c:41:11: warning: variable ‘capc_charge1’ set but not used [-Wunused-but-set-variable]
px.c: In function ‘cap_charge2’:
px.c:46:11: warning: variable ‘capc_charge2’ set but not used [-Wunused-but-set-variable]
px.c: In function ‘cap_charge3’:
px.c:51:11: warning: variable ‘capc_charge3’ set but not used [-Wunused-but-set-variable]
px.c:53:1: warning: control reaches end of non-void function [-Wreturn-type]
px.c: In function ‘cap_charge2’:
px.c:48:1: warning: control reaches end of non-void function [-Wreturn-type]
px.c: In function ‘cap_charge1’:
px.c:43:1: warning: control reaches end of non-void function [-Wreturn-type]
px.c: In function ‘main’:
px.c:32:1: warning: control reaches end of non-void function [-Wreturn-type]
/tmp/ccDqiD4u.o: In function `cap_charge1':
px.c:(.text+0xe5): undefined reference to `log'
/tmp/ccDqiD4u.o: In function `cap_charge2':
px.c:(.text+0x10f): undefined reference to `log'
/tmp/ccDqiD4u.o: In function `cap_charge3':
px.c:(.text+0x139): undefined reference to `log'
collect2: ld returned 1 exit status

cap_charge1 function and the 2,3 have arguments, but when you call them in the printfs, you don't pass any arguments to them!
Moreover, the body of them calculate something they store in a local variable. In the timeconstant you nicely return something.

Are you confused with the name of the function and the name of the variable? Don't! They are not the same.
Check this simple example in functions in C.

**Dobblaar** · 11-30-2013

Thank you very much, shortly after posting this i just started fresh, and re wrote the code from the one i posted above, i went through step by step and realized i had too many things happening without it being clear, i now got it working perfectly!

Thread: Values are not calculating?

Thread Tools

Search Thread

Display

Values are not calculating?

Similar Threads

Problem with program that uses a function to convert decimal values to binary values.

Calculating the lowest and highest values

Calculating min and max values of an arbitrary mesh.

help storing and calculating hex values

calculating maximum and minimum values for a basic C++ program