Array assignment error in C , What is wrong with my code?-CodePudding

I am trying this code in CodeBlocks but the result is some random numbers! I appreciate if you check the code and let me know what my mistake is. It should result in multipliers of 25:

#include <iostream>

using namespace std;

main(){

    const int array_size = 10;
    int numbers[array_size];
    int counter = 0;

    while(counter < array_size){
        numbers[counter] = 25 * counter;
        counter  ;
        cout << "number[" << counter << "] = " << numbers[counter] << endl;
    }
}

Thanks in advance.

CodePudding user response：

You are incrementing counter after setting the value of numbers[counter]. After that. numbers[counter] (with the new value of counter) is a new uninitialized element.

You should move the increment after the printing:

#include <iostream>

using namespace std;

int main(){

    const int array_size = 10;
    int numbers[array_size];
    int counter = 0;

    while(counter < array_size){
        numbers[counter] = 25 * counter;
        cout << "number[" << counter << "] = " << numbers[counter] << endl;
        counter  ;
    }
}

Or simply avoid using an array (in this case):

#include <iostream>

int main(){

    const int array_size = 10;
    int counter = 0;

    while(counter < array_size){
        std::cout << "number[" << counter << "] = " << 25 * counter << std::endl;
        counter  ;
    }
}

Another way is using two loops -- one for initialization and one for printing:

#include <iostream>

using namespace std;

int main(){

    const int array_size = 10;
    int numbers[array_size];
    int counter = 0;

    while(counter < array_size){
        numbers[counter] = 25 * counter;
        counter  ;
    }

    counter = 0;
    while(counter < array_size){
        cout << "number[" << counter << "] = " << numbers[counter] << endl;
        counter  ;
    }
}

CodePudding user response：

You are outputting an uninitialized element of the array after incrementing of the variable counter.

    counter  ;
    cout << "number[" << counter << "] = " << numbers[counter] << endl;

The reason of the error is usage of an inappropriate loop.

Instead of the while loop it is better to use for loop.

For example

for ( int counter = 0; counter < array_size; counter   ){
    numbers[counter] = 25 * counter;
    cout << "number[" << counter << "] = " << numbers[counter] << endl;
}

Pay attention to that the function main without parameters shall be declared like

int main()

That is you may not omit the function return type.

CodePudding user response：

change for this code

const int array_size = 10;
    int numbers[array_size];
    int counter = 0;

    while(counter < array_size){
        numbers[counter] = 25 * counter;
        cout << "number[" << counter << "] = " << numbers[counter] << endl;
        counter  ;
    }