Thread: Calc Program I made Tell me what u think

Originally posted by billholm


Enter equation: 4 + 4 + 10 /2 * 5 - 10
Answer: 23

It's kinda hard and I haven't even reached halfway.

i think this is what you need ;-)

3*(5+3)=24

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#include <stdio.h>
#define PLUS 1
#define MUL 2
#define NUMBER 3
#define LEFT_PAR 4
#define RIGHT_PAR 5
#define INFO(x) ((x)->info)
#define LEFT(x) ((x)->left)
#define RIGHT(x) ((x)->right)
#define VALUE(x) ((x)->value)

struct t_node {int info; int value; struct t_node *left; struct t_node *right;};

/* function declarations */

int gettoken(void); /* type of the last token */
struct t_node *construct_structure(void); /* constructs the structure, binary tree */
int evaluate_structure(struct t_node *); /* evaluates the structure */
void treeprint(struct t_node *); /* prints the tree */

int tokentype, num;
char operand[50];

struct t_node *tree;

int gettoken(void) {
int c;
char *number = operand;

while ((c = getchar()) == ' ' || c == '\t' || c == '\n'); /* Skip blanks */
if (c == '+')
return tokentype = PLUS;
else if (c == '*')
return tokentype = MUL;
else if (isdigit(c)) {
for (*number ++ = c; isdigit(c = getchar()); )
*number ++ = c;
*number = 0;
num = atoi(operand);
ungetc(c, stdin);
return tokentype = NUMBER;
}
else if (c == '(')
return tokentype = LEFT_PAR;
else if (c == ')') {
return gettoken();
}
else return tokentype = c;
}

struct t_node *construct_structure() {
struct t_node *tp;

gettoken();
tp = (struct t_node *) malloc(sizeof(struct t_node));
if (tokentype == LEFT_PAR) {
LEFT(tp) = construct_structure();
INFO(tp) = gettoken();
RIGHT(tp) = construct_structure();
}
else if (tokentype == NUMBER) {
INFO(tp) = tokentype;
VALUE(tp) = num;
LEFT(tp) = RIGHT(tp) = NULL;
}
else {
printf("Stg wrong! \n");
exit(1);
}
return tp;
}

int evaluate_structure(struct t_node *tp) {
switch (INFO(tp)) {
case PLUS : return evaluate_structure(LEFT(tp)) + evaluate_structure(RIGHT(tp)); break;
case MUL : return evaluate_structure(LEFT(tp)) * evaluate_structure(RIGHT(tp)); break;
case NUMBER : return VALUE(tp); break;
default : printf("What ???\n"); exit(1);
}
}

void treeprint(struct t_node *p) {
if (p) {
treeprint(LEFT(p));
switch (INFO(p)) {
case PLUS : printf("+\n"); break;
case MUL : printf("*\n"); break;
case NUMBER : printf("%d\n", VALUE(p)); break;
}
treeprint(RIGHT(p));
}
}
int main() {
tree = construct_structure();
treeprint(tree);
printf("result = %d\n", evaluate_structure(tree));
return 0;
}

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hi there just saw ur calc.c
the one in which u added colour

u r using scanf for the menu options which makes it very easy for the program to crash

type abcd or any alphabet on the prompt
and see what ur code says

secondly in the division operation

u havent handled when someone tries to divide by zero

that will also crash ur code

whenever u write code expect the user of ur code to be naive

if he types alphabets instead of numbers ur code goes berzerk

use fgets instead to scan the input from the user and then use sscanf to get the integers

hope this helps

cheers

Hare Krsna

how will ur program distingish teh difference between

2*3+5 and 2*(3+5)

the parantheses are a must case.
and the program i wrote here works perfectly if u enter rght data.
i dont care people who wnter wrong data