CODEWITHSUNDEEP
c++loops
SilverNightaFall
SilverNightaFall

Reputation: 4180

how to increment a referenced variable by 1

I am new to c++ and I am trying to increase cars starting with value 50, but only increase by one if the youdamage is greaters than cardamage. I want cars to hold its value for the next time it does through the loop. I hope this makes sense.

int Power (int &car);

int main(){
    int car = 50;
    // ...
    // ...
    // ...

    int carDamage = 0;
    int yourDamage = 0;
    // pick a random number between 1 to 50
    yourDamage = 0 + rand() % (50 - 0 + 1);
    carDamage = 0 + rand() % (50 - 0 + 1);
    cout << "You hit the car and cause damage of: " << carDamage << endl;
    cout << "The car hits you and causes damage of: " << yourDamage << endl;
    cout << endl;

    if(carDamage < yourDamage)
    {
        cout << "You win" << endl;
        cout << "You gain strength." << endl;
        cout << endl;
        int car = car + 1;
    }
    else
    {

Upvotes: 8

Views: 28356

Answers (6)

Martin Samson
Martin Samson

Reputation: 4090

By doing this:

int car = car + 1;

You are re-defining car as an integer.

see:

#include <stdio.h>
int car;
int main() {
    car = 0;
    for (int i = 0; i < 10; i++) {
        int car = 0;
        car++;
    }
    printf("%3d", car);
}

vs

#include <stdio.h>
int car;
int main() {
    car = 0;
    for (int i = 0; i < 10; i++) {
        car++;
    }
    printf("%3d", car);
}

Upvotes: 1

John Humphreys
John Humphreys

Reputation: 39294

I don't see a loop, but I'm going to hazard a guess that your problem is that you're doing this line:

int car = car + 1;

in your:

if(carDamage < yourDamage)

statement which means that you're redeclaring each time, resetting its value.

write the int car; outsize the statement and just do ++car; inside the loop where you originally wrote int car = car + 1;

Upvotes: 0

NickLH
NickLH

Reputation: 2645

Your problem is that when you say 

int car = car + 1;

You are basically creating a local variable called car (local to the if statement) which is assigned the value of 51 (since the original local scope variable (local to main) contains 50 and you add 1). This local variable (the on in the if statement) is destroyed once you get out of the if statement.

If you change this to

car = car + 1;

You are now modifying the variable local to main, and thus the update will be kept.

Upvotes: 0

Oscar Korz
Oscar Korz

Reputation: 2487

You are declaring a new variable car inside the if statement which hides the original car variable from the above scope. Removing the type will allow you to reference the existing variable instead of declaring a new one.

In short, change

int car = car + 1;

to

car = car + 1;

Upvotes: 0

littleadv
littleadv

Reputation: 20272

You're declaring a new variable shadowing the original one.

change

int car = car + 1;

to

car = car + 1;

Upvotes: 10

Mark Byers
Mark Byers

Reputation: 838226

You need to reassign to the same variable. You are declaring a new variable.

Change this:

int car = car + 1;

To this:

++car;

Upvotes: 9

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