programming C+++.i really dun know and confuse

[Nor farhana yaakub]

i
dun know how to 1. Write a program that uses a do-while loop to print the even numbers between 2 and 60, inclusive, each on a new line.

2. Write a program that asks the user to enter a number between 1 and 100 and uses a do-while loop to error trap the entry of the data. This means that the question will stay inside of the loop until a correct response is entered.

3.Write a program that asks the user to enter his/her test grades (enter -99 to quit). Print the AVERAGE of the test grades entered to the nearest tenth. Use a do-while loop for this program.
please,i really need to know the program listing and the coding,so maybe i'll try to understand it by myself

[Banfa]

1. Write a program that uses a do-while loop to print the even numbers between 2 and 60, inclusive, each on a new line.

If this is too hard try

1. Write a program that uses a do-while loop to print all the numbers between 1 and 60, inclusive, each on a new line.

You will need to know

1. How to declare an integer variable, the basic sytanx for variable declaration is
   
   <type> <name>;
   
   e.g. int i;
2. How to increment an integer variable, there are several ways for doing this, these statements all do the same thing, add 1 onto i
   i = i + 1;
   i += 1;
   i++;
   ++i;
3. How to write a do-while loop, the syntax is
   do {
   /* code statements here */
   while( <endCondition > );
   
   While the end condition is true the loop keeps looping, when the end condition is false the loop ends, for example
   
   do {
   /* code statements here */
   while( i<=20 );
   
   Loops until I has a value greater than 20
4. How to output the value of an integer to the console, you can use the function printf, it takes a format string that tells it what to output, for an integer
   
   printf("The value is %d\n", i);

Now have an attempt yourself and post it here

[Nor farhana yaakub]

i have try like this...thanks ya..now much more better understanding.
#include<iostre am>
using namespace std;
int main()
{

int x = 1;
do

{

cout << x << endl;
x += 1;

}

while(x <= 60);
}

[Nor farhana yaakub]

how about if i change the do-while loop to for loop???lets say if i want to print no from 2 till 60...means the result will be printed out like this...2.4.6.8. 10........60... but i have try it like this using "for loop",but why when i use x+=2,the result come out wrongly????..i realised i have to use x+=1...but,why? ??
thanks for your leisure....

[D_C]

The way you have it now, it starts at 1, and increments by 1, giving 1, 2, 3, ... 60.
If you want 2, 4, 6, ... 60, then you need to start at 2, and increment by 2.

for loop syntax:

for(INITIALIZE; CONDITION; INCREMENT)
{
  statements...
}

To convert your program as is, it would be:

for(int x = 1; x <= 60; x+= 1)
{
  cout << x << endl;
}

The above will loop while x is less than or equal to 60, starting with x = 1, incrementing x by one (x += 1) each time. The result will be 1, 2, 3, ... 60.

[Nor farhana yaakub]

thanks,friend.. i understand about that....