rpn

#define STACK_DEPTH 100
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<ctype.h>
#include<math.h>
double stack[STACK_DEPTH];
int sp=STACK_DEPTH;
double pop(void)
{
    if(sp<STACK_DEPTH){
       return stack[sp++];
    }else{
       return 0.0;
    }
}
void push(double f)
{
     if(sp>0)
        stack[--sp]=f;
      }
int getword(char* dst, const char* str, int limit)
 {
    int i, j, len = strlen(str);
    for(i=0; i<len && isspace(str[i]); i++);
    for(j=0; j<limit && (j+i)<len && !isspace(str[i+j]); j++)
    dst[j]=str[i+j];
    dst[j]='\0';
    return i+j;
}
int main(void)
{
    printf("Podaj wyrażenie w rpn:\n");
    double op2;
    char line[100], tmp[100];
    int i, c;
    while(1){
        i = 0;
        fgets(line, 100, stdin);
        while((c=getword(tmp, &line[i], 100)) && strlen(tmp)){
            if(strcmp(tmp, "sin")==0)
                push(sin(pop()));
            else if(strcmp(tmp, "cos")==0)
                push(cos(pop()));
            else if(strcmp(tmp, "pow")==0){
                op2 = pop();
                push(pow(pop(),op2));
            }
            else if(strcmp(tmp, "+")==0)
                push(pop()+pop());
            else if(strcmp(tmp, "-")==0){
                op2 = pop();
                        push(pop()-op2);}
            else if(strcmp(tmp, "*")==0)
                push(pop()*pop());
            else if(strcmp(tmp, "/")==0){
                op2 = pop();

                            push(pop()/op2);}
            else if(strcmp(tmp, "=")==0)
                printf("%f\n", pop());
            else
            push(atof(tmp));
            i+=c;
        }
        if (line[0] == '\n') break;
    }
    return 0;
}