CL calculator

[mike_g]

When I did C in college I always wondered if there was any point to the command line progs we used to have to make; now I'm using Linux it seems they may have a use after all :)

Anyway, heres a simple calculator prog I knocked up that could come in handy from time to time:

#include <stdio.h>
#include <stdlib.h>

double Calc(double left, char op, double right)
{
switch(op)
{
case '+': return left + right;
case '-': return left - right;
case 'x': return left * right;
case '/': return left / right;
default:
printf("Invalid operator.\nValid ops: + - x /\n");
exit(EXIT_FAILURE);
}
}

int main(int argc, char* argv[])
{
if(argc < 4)
{
printf("Error: Not enough parameters.\n");
exit(EXIT_FAILURE);
}
if(argc % 2)
{
printf("Error: Invalid parameters.\n");
exit(EXIT_FAILURE);
}
double left=strtod(argv[1], NULL), right;
int i;
for(i=2; i<argc; i+=2)
{
right = strtod(argv[i+1], NULL);
left = Calc(left, argv[i][0], right);
}
printf("%f\n", left);
exit(EXIT_SUCCESS);
}

It read expressions from left to right, as opposed to BODMAS ordering. Also each operator/operand needs to be split by a space. It would probably be better if the entire expression was fed into the prog as a single srting then broke down, but that would require a whole load of extra code which would spoil the simplicity of it all.

Anyway, have fun :)