Calculator Operand

[xetehkah]

This is a part of the main function of my calculator:

	if(op == '+')
  					{
  						ans = ans + m;  						
  					}
  					else if(op == '-')
  					{
  						ans = ans - m;
  					}
  					else if(op == '*')
  					{
  						ans = ans * m;
  					}
  					else if(op == '/')
  					{
  						ans = ans / m;
  					}
  					else if(op == '%')
  					{
  						ans = ans % m;
  					}
  					else if(op == '^')
  					{
  						ans = ans ^ m;

what I need to learn is on how to create "operands" like "abs" and "neg"

so that when I input something like "abs -10 + 10" the result would be 20
or " neg -38 + 2" the result would be 40...

even if i tried

if(op == 'abs')
  {
  	if ( m >= 0)
           return m;
        else
           return -m;

it wouldnt work...

[carrotcake1029]

strcmp or strncmp

[xetehkah]

what statements should I use with that?

anyway any tutorials on using strcmp or strncmp you could recomment?

im having a hard time understanding strings...T_T

[Griever]

if( strcmp("abs",op)==0)
  {
  	if ( m >= 0)
           return m;
        else
           return -m;
    }

use strcmp (string compare).it returns the difference of the ASCII values of each string.when op contains "abs", this function will return 0.don't forget to include string.h .

 #include <string.h>

[xetehkah]

well I put the code above the previous codes i posted.

when my input is "abs -50"(with space) it just returns 0.

should I change char op to int op?

[Griever]

would you mind posting the part of the code where program receives input?

[bertazoid]

well I put the code above the previous codes i posted.

when my input is "abs -50"(with space) it just returns 0.

should I change char op to int op?

op should be a string (an array of characters) so the declaration of op should be char op[SIZE]; where SIZE is a positive integer of your choosing giving the size of the array.

[itCbitC]

Post the code for parsing the operator "abs".
After coming across "abs" grab the operand by skipping over any whitespace.
What is the datatype of "m"?

[xetehkah]

heres more on the code.

sorry if i cant put it all...

fgets(line, 80, fr);
   
   while(fgets(line, 80, fr) != NULL)
   {   		
		p = strtok(line," ");
		
  		while (p != NULL)  		
  		{  			
  			n = n++;

some code here....

  				else
  				{
  					if(*p == 'U')
  					{
  						m = U;
  					}
  					else if(*p == 'P')
  					{
  						m = P;
  					}
  					else
  					{
  						m = atoi(p);
  					}					
  					if(op == '+')
  					{
  						ans = ans + m;  						
  					}
  					else if(op == '-')
  					{
  						ans = ans - m;
  					}
  					else if(op == '*')
  					{
  						ans = ans * m;
  					}
  					else if(op == '/')
  					{
  						ans = ans / m;
  					}
  					else if(op == '%')
  					{
  						ans = ans % m;
  					}
  					else if(op == '^')
  					{
  						ans = ans ^ m;
  					}
  				}
  			}

i tried putting if

( strcmp("abs",op)==0)
  {
  	if ( m >= 0)
           return m;
        else
           return -m;
    }

above the addition code but it wouldnt work...

this calculator uses fprintf and fscanf...~_~

another thing how do i get the exponent to work?

it doesnt seem to work...~_~

[matsp]

  					if(op == '+')
  					{
  						ans = ans + m;  						
  					}
  					else if(op == '-')
  					{
  						ans = ans - m;
  					}
  					else if(op == '*')
  					{
  						ans = ans * m;
  					}
  					else if(op == '/')
  					{
  						ans = ans / m;
  					}
  					else if(op == '%')
  					{
  						ans = ans % m;
  					}
  					else if(op == '^')
  					{
  						ans = ans ^ m;
  					}

Surely this should be a switch-statement.

Red: Are you actually intending to do exclusive or - or did you mean "to the power of", in which case your code should not use ^.

( strcmp("abs",op)==0)
  {
  	if ( m >= 0)
           return m;
        else
           return -m;
    }

What is op, and how was it assigned?

[xetehkah]

   int n = 0, m = 0, ans = 0, lcnt = 0, U = 0, P = 0;
   char line[80], op;
   char *p;

as for the power, it should use the "^" symbol~
like 5 ^ 2 = 25

T_T

should I use pow()?

[matsp]

   int n = 0, m = 0, ans = 0, lcnt = 0, U = 0, P = 0;
   char line[80], op;
   char *p;

as for the power, it should use the "^" symbol~
like 5 ^ 2 = 25

T_T

should I use pow()?

So, op is a single character, so it can NEVER match "abs", can it?

And yes, you need to use pow() or something similar for the ^ operator.

--
Mats

[xetehkah]

so how should I inset pow() in that?

i tried changing op to op[size] but the other operators had the problem...

[matsp]

so how should I inset pow() in that?

Not sure what you mean with that... You need to use pow() to calculate power - unless you write your own code to do something similar.

i tried changing op to op[size] but the other operators had the problem...

You haven't really shown us the bit of code that does the "split input into operations and operands", so it's hard to know what you need to do in understanding your expression and turning "ABS" into an "absolute operator".

--
Mats

[IceDane]

Just a few hints.

• Strings in C(Or character arrays to be specific), cannot be compared to each other using the comparison operator (==)
• Use strncmp for C-style string comparisons
• Make sure that op is a character array, not a single character

That's all we can tell you if you don't post all the code. Do so, and you will receive more help.