Create Calculator in C language that evaluate user input math expressions and pr
ID: 3865647 • Letter: C
Question
Create Calculator in C language that evaluate user input math expressions and produce answer. The program will continue to evaluate expression until ‘exit’ is entered. Tasks: Ask user to enter expressions example: (9.342 + 2)^3 + 5!/6*sin(3.5*pi) – 3*cos( 2!) 34-4^(3+2) + ln( 32 * tan(3pi)) Check to see if expression is valid -balance bracket? -illegal entry - expression may have empty space between operators but your program will remove it Display postfix expression. Use postfix expression to calculate value and display result. Must use expression tree (implement using linked list) & stacks (or queues). Support operation tokens: 1: + - * / % ^ pi () 2: ! log( ) ln( ) sin() cos() tan( ) 3: { } 4: constant pi=3.14159 5: %=modulus 6: ^ =exponents 7: ! = factorial 8: log(x)=log10 ( x ) Do not have the core logic in your main(). The main() should only have function calls and basic programme control and user input. Keep your code modular
Explanation / Answer
#include <stdio.h> /* Standard input/output */
#include <string.h> /* For string functions */
#include <ctype.h> /* For classifying characters */
#include <stdlib.h> /* For converting strings to numeric values */
#include <math.h> /* For power() function */
void main()
{
char input[256]; /* Input expression */
char number_string[30]; /* Stores a number string from input */
char op = 0; /* Stores an operator */
unsigned int index = 0; /* Index of the current a character in input */
unsigned int to = 0; /* To index for copying input to itself */
size_t input_length = 0; /* Length of the string in input */
unsigned int number_length = 0; /* Length of the string in number_string */
double result = 0.0; /* The result of an operation */
double number = 0.0; /* Stores the value of number_string */
printf(" To use this calculator, enter any expression with"
" or without spaces");
printf(" An expression may include the operators:");
printf(" +, -, *, /, %%, or ^(raise to a power).");
printf(" Use = at the beginning of a line to operate on ");
printf(" the result of the previous calculation.");
printf(" Use quit by itself to stop the calculator. ");
/* The main calculator loop */
while(strcmp(gets(input), "quit") != 0)
{
input_length = strlen(input); /* Get the input string length */
/* Remove all spaces from the input by copy the string to itself */
/* including the string terminating character */
for(to = 0, index = 0 ; index<=input_length ; index++)
if(*(input+index) != ' ') /* If it is not a space */
*(input+to++) = *(input+index); /* Copy the character */
input_length = strlen(input); /* Get the new string length */
index = 0; /* Start at the first character */
if(input[index]== '=') /* Is there =? */
index++; /* Yes so skip over it */
else
{ /* No - look for the left operand */
/* Look for a number that is the left operand for the 1st operator */
/* Check for sign and copy it */
number_length = 0; /* Initialize length */
if(input[index]=='+' || input[index]=='-') /* Is it + or -? */
*(number_string+number_length++) = *(input+index++); /* Yes so copy it */
/* Copy all following digits */
for( ; isdigit(*(input+index)) ; index++) /* Is it a digit? */
*(number_string+number_length++) = *(input+index); /* Yes - Copy it */
/* copy any fractional part */
if(*(input+index)=='.') /* Is it decimal point? */
{ /* Yes so copy the decimal point and the following digits */
*(number_string+number_length++) = *(input+index++); /* Copy point */
for( ; isdigit(*(input+index)) ; index++) /* For each digit */
*(number_string+number_length++) = *(input+index); /* copy it */
}
*(number_string+number_length) = ''; /* Append string terminator */
/* If we have a left operand, the length of number_string */
/* will be > 0. In this case convert to a double so we */
/* can use it in the calculation */
if(number_length>0)
result = atof(number_string); /* Store first number as result */
}
/* Now look for 'op number' combinations */
for(;index < input_length;)
{
op = *(input+index++); /* Get the operator */
/* Copy the next operand and store it in number */
number_length = 0; /* Initialize the length */
/* Check for sign and copy it */
if(input[index]=='+' || input[index]=='-') /* Is it + or -? */
*(number_string+number_length++) = *(input+index++); /* Yes - copy it. */
/* Copy all following digits */
for( ; isdigit(*(input+index)) ; index++) /* For each digit */
*(number_string+number_length++) = *(input+index); /* copy it. */
/* copy any fractional part */
if(*(input+index)=='.') /* Is is a decimal point? */
{ /* Copy the decimal point and the following digits */
/* Copy point */
*(number_string+number_length++) = *(input+index++);
for( ; isdigit(*(input+index)) ; index++) /* For each digit */
*(number_string+number_length++) = *(input+index); /* copy it. */
}
*(number_string+number_length) = ''; /* terminate string */
/* Convert to a double so we can use it in the calculation */
number = atof(number_string);
/* Execute operation, as 'result op= number' */
switch(op)
{
case '+': /* Addition */
result += number;
break;
case '-': /* Subtraction */
result -= number;
break;
case '*': /* Multiplication */
result *= number;
break;
case '/': /* Division */
/* Check second operand for zero */
if(number == 0)
printf(" Division by zero error! ");
else
result /= number;
break;
case '%': /* Modulus operator - remainder */
/* Check second operand for zero */
if((long)number == 0)
printf(" Division by zero error! ");
else
result = (double)((long)result % (long)number);
break;
case '^': /* Raise to a power */
result = pow(result, number);
break;
default: /* Invalid operation or bad input */
printf(" Illegal operation! ");
}
}
printf("= %f ", result); /* Output the result */
}
}