Help with programming in C++

if (statement)
{
    (block of code)
}
else
{
    (block of code)
}

int x, i, sum;
cin >> x
while (x < 0 )
{
 cout << " please enter pos number" << endl;
 cin >> x;
}

for (i = 0; i < x+1; i++)
{
 sum = sum + i;
)

cout << sum << endl;

// rectangle one:
if (area1 > area2);
{
    cout << "The first rectangle is larger than the second one.\n";
}
else (area1 < area2);
{
    cout << "The second rectangle is larger than the first one.\n";
}
return 0;

int num1 = rand();
int num2 = rand();
cout << num1 << "\n+" << num2 << endl;
cin >> answer;

if ( answer == (num1+num2) )
{
    cout << "gz";
}
else
{
    cout << "Sorry the wrong answer is: " << num1+num2 << endl;
}

if (runner1 > runner 2 && runner1 > runner3)
{
    runner 1 wins!
}

class Runner {
int time;
}

Runner jack;
jack.time = 10;

int runners[name][time] = {
   A, 1,
   B, 2,
   C, 3
};

cin >> number;
int x = 0;
while (x < number)
{
   x++;
} // this will loop until X = number

alternatively a more pretty loop would be

for (int x = 0; x < number; x++)
{
   // do whatever here.
}

for ( variables; condition; increment/decrement )

for (;;).

// rectangle one:
if (area1 > area2);
{
    cout << "The first rectangle is larger than the second one.\n";
}
else (area1 < area2);
{
    cout << "The second rectangle is larger than the first one.\n";
}
return 0;

if (area1 > area2) // area 1 greater than area 2
{
   cout << "blablah";
}
else if (area2 > area 1) // the else here is so that if the first if checks through as true, the elses will be ignored.
{
   cout << "blahblah"
}
else // both areas are equal
{
   cout << "blahblah"
}

int x = 0;
cin >> x;
if (cin.good() > 0)
{
    cout << "user input is: " << x << endl;
}
else
{
    cout << "user input is bad" << endl;
}

#include <string>
#include <iostream>
#include <conio.h>

using namespace std;

int main()
{
	cout << "Input number or w/e\n";
	string input;
	cin >> input;
	for (int x = 0; x < input.size(); x++)
	{
		if ( input[x] < 48 && input[x] > 57 )
		{
			cout << "Only 0-9";
			break;
		}
	}

	int validated = atoi(input.c_str());
	if (validated > 0)
        {
		cout << validated;
        }
        else
        {
            cout << "Number must be over 0\n";
        }

	getch();
	return 0;
}

int input;
cin >> input;
if (input > 0)
{
	// do whatever here
}
else
{
	// tell the user his input was bad.
}

if (area1 > area2) // area 1 greater than area 2
{
   cout << "blablah";
}
else 
{
   // the else here is so that if the first if checksthrough as true, the elses will be ignored.
    if (area2 > area1) 
    {
       cout << "blahblah";
    }
   else // both areas are equal
   {
     cout << "blahblah";
   }
}

#include "stdafx.h"
#include <iostream>
#include <conio.h>

using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
	int nInputNumber = 0;
	int nCounter = 0;
	int anNumbers[100000];
	int nMax = INT_MIN;
	int nMin = INT_MAX;

	cout << "This program will input a series of numbers and show the maximum and minimum\n";

	cout << "Enter a number(-99 to finish): ";
	cin >> nInputNumber;

	while(nInputNumber != -99) 
	{
		anNumbers[nCounter] = nInputNumber;
		nCounter++;

		cout << "Enter a number(-99 to finish): ";
		cin >> nInputNumber;
	}

	for(int i = 0; i < nCounter; i++) {
		int nNum = anNumbers[i];

		if(nNum > nMax) 
			nMax = nNum;
		if(nNum < nMin) 
			nMin = nNum;
	}

	if(nCounter == 0)
		cout << "No numbers entered";
	else
		cout << "Maximum: " << nMax << endl << "Minimum: " << nMin;

	cout << "\nEnter any key to quit . . .";

	_getch();
	
	return 0;
}

#include <iostream>
using namespace std;

int main()

{
    int years = 0;
            cout << "Years Growth\n";
            cout << "_____________________\n";
        while (years <= 25)
        {
            cout << years << "\t\t" << (years + 1.5) <<endl;
            years++;
        }
    return 0;
}

int years = 1;
float growth = 1,5;
while (years <= 25)
{
    cout << "Year " << years << " - " << growth << " millimeters" << endl;
    years++;
    growth += 1.5;
}

int x = 0;
cin >> x;
if (cin.good() > 0)
{
    cout << "user input is: " << x << endl;
}
else
{
    cout << "user input is bad" << endl;
}

#include <string>
#include <iostream>
#include <conio.h>

using namespace std;

int main()
{
	cout << "Input number or w/e\n";
	string input;
	cin >> input;
	for (int x = 0; x < input.size(); x++)
	{
		if ( input[x] < 48 && input[x] > 57 )
		{
			cout << "Only 0-9";
			break;
		}
	}

	int validated = atoi(input.c_str());
	if (validated > 0)
        {
		cout << validated;
        }
        else
        {
            cout << "Number must be over 0\n";
        }

	getch();
	return 0;
}

int input;
cin >> input;
if (input > 0)
{
	// do whatever here
}
else
{
	// tell the user his input was bad.
}

if(cin.fail()){
   // print bad stuff
   return -1;
}

if (input[x] < 48 && input[x] > 57 )

if (input[x] < '0' && input[x] > '9' )