Evaluate an array expression with numbers, + and -
Last Updated :
19 Sep, 2023
Given an array arr[] of string type which consists of strings "+", "-" and Numbers. Find the sum of the given array.
Examples :
Input : arr[] = {"3", "+", "4", "-", "7", "+", "13"}
Output : Value = 13
The value of expression 3+4-7+13 is 13.
Input : arr[] = { "2", "+", "1", "-8", "+", "13"}
Output : Value = 8
Approach :
- First of all, initialize the sum i.e, sum = 0.
- Start traversing the array.
- As there is string of numbers at every even position of the array, so convert this string into integer and store in a variable value by using stoi function in C++.
- As there is operator at every odd position, check if the operator is '+' or '-'. If it is '+', then add the value to the sum, else subtract from the sum.
- Finally, return the sum obtained.
Below is the implementation of the above approach :
C++
// C++ program to find sum of given array of
// string type in integer form
#include <bits/stdc++.h>
using namespace std;
// Function to find the sum of given array
int calculateSum(string arr[], int n)
{
// if string is empty
if (n == 0)
return 0;
string s = arr[0];
// stoi function to convert
// string into integer
int value = stoi(s);
int sum = value;
for (int i = 2; i < n; i = i + 2)
{
s = arr[i];
// stoi function to convert
// string into integer
int value = stoi(s);
// Find operator
char operation = arr[i - 1][0];
// If operator is equal to '+',
// add value in sum variable
// else subtract
if (operation == '+')
sum += value;
else
sum -= value;
}
return sum;
}
// Driver Function
int main()
{
string arr[] = { "3", "+", "4", "-",
"7", "+", "13" };
int n = sizeof(arr) / sizeof(arr[0]);
cout << calculateSum(arr, n);
return 0;
}
// Java program to find sum of given array of
// string type in integer form
import java.io.*;
class GFG {
// Function to find the sum of given array
public static int calculateSum(String arr[], int n)
{
// if string is empty
if (n == 0)
return 0;
String s = arr[0];
// parseInt function to convert
// string into integer
int value = Integer.parseInt(s);
int sum = value;
for (int i = 2; i < n; i = i + 2)
{
s = arr[i];
// parseInt function to convert
// string into integer
value = Integer.parseInt(s);
// Find operator
char operation = arr[i - 1].charAt(0);
// If operator is equal to '+',
// add value in sum variable
// else subtract
if (operation == '+')
sum += value;
else
sum -= value;
}
return sum;
}
// Driver code
public static void main (String[] args)
{
String arr[] = { "3", "+", "4", "-",
"7", "+", "13" };
int n = arr.length;
System.out.println( calculateSum(arr, n));
}
}
// This code in contributed by Upendra bartwal
# Python3 program to find sum of given
# array of string type in integer form
# Function to find the sum of given array
def calculateSum(arr, n):
# if string is empty
if (n == 0):
return 0
s = arr[0]
# stoi function to convert
# string into integer
value = int(s)
sum = value
for i in range(2 , n, 2):
s = arr[i]
# stoi function to convert
# string into integer
value = int(s)
# Find operator
operation = arr[i - 1][0]
# If operator is equal to '+',
# add value in sum variable
# else subtract
if (operation == '+'):
sum += value
else:
sum -= value
return sum
# Driver Function
arr = ["3", "+", "4", "-","7", "+", "13"]
n = len(arr)
print(calculateSum(arr, n))
# This code is contributed by Smitha
// C# program to find sum of given array of
// string type in integer form
using System;
class GFG {
// Function to find the sum of given array
public static int calculateSum(string []arr,
int n)
{
// if string is empty
if (n == 0)
return 0;
string s = arr[0];
// parseInt function to convert
// string into integer
int value = int.Parse(s);
int sum = value;
for (int i = 2; i < n; i = i + 2)
{
s = arr[i];
// parseInt function to convert
// string into integer
value = int.Parse(s);
// Find operator
char operation = arr[i - 1][0];
// If operator is equal to '+',
// add value in sum variable
// else subtract
if (operation == '+')
sum += value;
else
sum -= value;
}
return sum;
}
// Driver code
public static void Main ()
{
string []arr = { "3", "+", "4", "-",
"7", "+", "13" };
int n = arr.Length;
Console.Write(calculateSum(arr, n));
}
}
// This code in contributed by nitin mittal.
<?php
// php program to find sum of given
// array of string type in integer form
// Function to find the
// sum of given array
function calculateSum($arr,$n)
{
// if string is empty
if ($n == 0)
return 0;
$s = $arr[0];
// stoi function to convert
// string into integer
$value = (int)$s;
$sum = $value;
for ($i = 2; $i < $n; $i = $i + 2)
{
$s = $arr[$i];
// cast to convert
// string into integer
$value = (int)$s;
// Find operator
$operation = $arr[$i - 1];
// If operator is equal to '+',
// add value in sum variable
// else subtract
if ($operation == '+')
$sum += $value;
else if ($operation == '-')
$sum -= $value;
}
return $sum;
}
// Driver code
$arr = array("3", "+", "4", "-",
"7", "+", "13" );
$n = sizeof($arr) / sizeof($arr[0]);
echo calculateSum($arr, $n);
// This code is contributed by mits
?>
<script>
// Javascript program to find sum of given array of
// string type in integer form
// Function to find the sum of given array
function calculateSum(arr, n)
{
// if string is empty
if (n == 0)
return 0;
let s = arr[0];
// parseInt function to convert
// string into integer
let value = parseInt(s);
let sum = value;
for (let i = 2; i < n; i = i + 2)
{
s = arr[i];
// parseInt function to convert
// string into integer
value = parseInt(s);
// Find operator
let operation = arr[i - 1][0];
// If operator is equal to '+',
// add value in sum variable
// else subtract
if (operation == '+')
sum += value;
else
sum -= value;
}
return sum;
}
let arr = [ "3", "+", "4", "-", "7", "+", "13" ];
let n = arr.length;
document.write(calculateSum(arr, n));
// This code is contributed by vaibhavrabadiya117.
</script>
Time Complexity: O(n)
Auxiliary Space: O(1)
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