Evaluate an array expression with numbers, + and

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

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach :
1) First of all, initialize the sum i.e, sum = 0.
2) Start traversing the array.
3) 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++.
4) 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.
5) 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

// 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 

Python 3

# 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#

// 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 
// 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  
?> 

Output :

Time Complexity : O(n)

My Personal Notes

Evaluate an array expression with numbers, + and –

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

C++

Java

Python 3

C#

PHP

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Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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C#

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