Решение задачи String 23

#include <bits/stdc++.h>

using namespace std;

int main()
{
    string s;
    cin >> s;
    int res = s[0] - 48, operation;
    for(int i = 1; i < s.size(); ++i){
        if(s[i] == '+')
            operation = 1;
        else if(s[i] == '-')
            operation = -1;
        else
            res += operation * (s[i] - 48);
    }
    cout << res;
    return 0;
}

# -*- coding: utf-8 -*-
import random
import string
import numpy as np

def RndExpr():
    N = random.randrange(2,11)
    lst_digit = list(np.random.choice(list(string.digits), N))
    lst_oper = list(np.random.choice(['+','-'], N-1))
    result = [None]*(2*N - 1)
    result[::2] = lst_digit
    result[1::2] = lst_oper
    return "".join(result)


for i in range(0,5):
    s = RndExpr()
    print()
    print(s, "=" ,eval(s))
    oper = s[1::2]
    j = 0
    result = int(s[0])
    for x in oper:
        digit = int(s[2*j+2])
        if x == '+':
            result += digit
        else:
            result -= digit
        #print(s[2*j+2],x,result)
        j += 1
    #print(oper)
    print(s, "=" ,result)
									

program String23;
var
  i,Rez,Operation:integer;
 
  S:string;
 
begin
 Write('S:');
 Readln (S);
 Rez:=ord(S[1])-48;
 
 for i:=2 to Length(S) do
   if (ord(S[i]) in  [48..57]) then Rez:=Rez+operation*(ord(S[i])-48)
   else if (ord(S[i]) = 43) then Operation:=1 //+
   else if (ord(S[i]) = 45) then Operation:=-1; //-
 
 Writeln(Rez);
end.