I have an assignament due tomorrow

**pythonary** · 11-27-2022

the assignament is basically for begginers, we have to build a logical statement calculator:
the statement is from the form (variable2 operation variable1)

the operations in the statements are : '>', '<', '='
and between two or more statement the logical operations could be :
'|' (or) , '&' (and) '~' (not)
if the input was ((a>b)&(1>2)|(5=3)) the function should return 0.

and therse no restriction on how many statements there could be
PS: we are not allowed to use strings or arrays.

examples for outputs:
~(a>b)The statement is true.
(a>b)&(2<3)The statement is false.
(2>3)|~(a>b)&(C>d)The statement is false.
(200>100)The statement is true.
(b=B)The statement is true.

**Salem** · 11-28-2022

> (a>b)&(2<3)The statement is false.
Do a and b have values, in the usual sense of a variable name has a value.
In which case, the truth value depends on those values.

> I have an assignament due tomorrow
That's unfortunate.

**flp1969** · 11-28-2022

Originally Posted by Salem

> I have an assignament due tomorrow
That's unfortunate.

Indeed

**pythonary** · 11-29-2022

Originally Posted by Salem

> (a>b)&(2<3)The statement is false.
Do a and b have values, in the usual sense of a variable name has a value.
In which case, the truth value depends on those values.

so the input has to be a char, so a and b are technically the a and b in the ascii table
I think I a have an idea but I want some help from someone with more experience

> I have an assignment due tomorrow
That's unfortunate.

the lecturer delayed it

**Crutoy37** · 11-29-2022

Originally Posted by pythonary

the lecturer delayed it

How far did you get? I'll be working on something similar soon.

**Salem** · 11-29-2022

> I think I a have an idea but I want some help from someone with more experience
We await your attempt.

**pythonary** · 11-30-2022

So i thought of creating two different function, the first one is gonna be statement scanning
and the second one is gonna be calculating the statements .

so this is my statement receiving function: I hope you can provide me with any shorter substitute or any improvement :]

Code:

int Statement()
{
  char in, op;                  // in as in input and op as in operation
  int result, not = 0, val1 = 0, val2 = 0;
  scanf("%c", &in);
  if (in == '~') {
    not = 1;
    scanf("%c", &in);
    if (in != '(') {
      printf("You have a syntax error in your statement\n");
      return 0;
    }
  }
  //first value
  scanf("%c", &in);
  if ((in <= 'f' && in >= 'a') || (in <= 'F' && in >= 'A')) {
    val1 = (int) in;
    scanf("%c", &in);
    if (in == '<' || in == '>' || in == '=') {
      op = in;
    } else {
      printf("You have a syntax error in your statement\n");
      return 0;
    }

  }
  if (in <= '9' && in >= '0') {
    do {
      val1 *= 10;
      val1 += (int) in;
      scanf("%c", &in);
    } while (in <= '9' && in >= '0');
    op = in;
  } else {
    printf("You have a syntax error in your statement\n");
    return 0;
  }

  // second value
  scanf("%c", &in);
  if ((in <= 'f' && in >= 'a') || (in <= 'F' && in >= 'A')) {
    val2 = (int) in;
    scanf("%c", &in);
    if (in == '<' || in == '>' || in == '=') {
      op = in;
    } else {
      printf("You have a syntax error in your statement\n");
      return 0;
    }

  }
  if (in <= '9' && in >= '0') {
    do {
      val2 *= 10;
      val2 += (int) in;
      scanf("%c", &in);
    } while (in <= '9' && in >= '0');
    op = in;
  } else {
    printf("You have a syntax error in your statement\n");
    return 0;
  }
  if (op == '=') {
    result = val1 == val2;
  }
  if (op == '>') {
    result = val1 > val2;
  }
  if (op == '<') {
    result = val1 < val2;
  }
  if (not == 1) {
    return !result;
  } else
    return result;
}

**~~kodax~~** · 11-30-2022

due tomorrow

Cheap trick to force someone else to do your stuff..

Code:

in <= '9' && in >= '0'

Remove this.
Keep it simple.

Code:

printf("You have a syntax error in your statement\n");

Remove this.
For now, don't worry about error checking.

There is a risk of int32 overflow.
I don't expect you to handle int32 overflow.

**~~kodax~~** · 11-30-2022

Code:

/* main.m, Simple Calculator, Created by Great on 10/30/22. */


#import <Foundation/Foundation.h>


int enter_value(int);
int enter_operator(void);
int calculate(int, int, char);


int enter_value(int tag) {
    
    int value[2];
    
    printf("\nEnter Value %d: ", tag);
    scanf("%d", value);
    
    return value[0];
}


int enter_operator(void) {
    
    char operator[2];
    
    printf("\nEnter Operator: ");
    scanf("%s", operator);
    
    return operator[0];
}


int calculate(int value1, int value2, char operator) {
    
    if ('=' == operator && value1 == value2) {
        printf("\nResult: True.\n\n");
        
    } else if ('>' == operator && value1 > value2) {
        printf("\nResult: True.\n\n");
        
    } else if ('<' == operator && value1 < value2) {
        printf("\nResult: True.\n\n");
        
    } else {
        printf("\nResult: False.\n\n");
        
    }
    
    return 0;
}


int main(int argc, const char *argv[]) {
    
    int value1 = 0;
    int value2 = 0;
    char operator = 0;
    
    value1 = enter_value(1);
    value2 = enter_value(2);
    operator = enter_operator();
    calculate(value1, value2, operator);
    
    return 0;
}

**pythonary** · 11-30-2022

Thank you for your effort, but I’m not allowed to use arrays or strings. And only use the stdio and math libraries.

**~~kodax~~** · 11-30-2022

This is the correct way to do it.

**pythonary** · 11-30-2022

I’m really thankful. And I know that this the correct way, but Im simply not allowed to use those stuff. If I use them imma get 0/100

**Salem** · 11-30-2022

TBH, you need to define the grammar before you write the code.

I mean it might work for your examples at the moment, but something like
((((((a>b))))))
is going to blow it up.

compiler construction - How to define a grammar for a programming language - Stack Overflow
Introduction to Programming Languages/Grammars - Wikibooks, open books for an open world

Like
log_op ::= "|" | "&"
paren_expr ::= "(" rel_expr ")"
rel_expr ::= symbol relop symbol
relop ::= "<" | "=" | ">"
symbol ::= "0" | "1" ... "Y" | "Z"

Which you turn into functions

Code:

int symbol() {
  int ch = getchar();
  if ( ch >= '0' && ch <= '9' ) return ch;
  if ( ch >= 'a' && ch <= 'z' ) return ch;
}

int rel_expr( ) {
  int s1 = symbol();
  int op = relop();
  int s2 = symbol();
  if ( op == '<' ) return s1 < s2;
  // etc
}

**pythonary** · 11-30-2022

how do I build the paren_expr fuction?

**Salem** · 11-30-2022

Originally Posted by pythonary

how do I build the paren_expr fuction?

You first call getchar() and expect that it's a '('
Then you call rel_expr to handle the relational expression.
Then you call getchar() and expect that it's a ')'

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