// cycles

do ..while:

- the syntax:

do
{

   statements;

}while(condition);    // DO NOT FORGET THE SEMICOLON!!!

EX.:

//what is missing here ..???

do
{
  cout<<"please, enter the value of a: "<<endl;
  cin>>a;
  
  if(a<0)
   cout<<" - not a good value! - try it again! "<<endl;
}while(a<0);

****************

while(condition)
{
  statements;
}

EX.:

//what is missing here ..???

while(a>0)
{
  cout<<"the value of a is: "<<a<<endl;
  a-=7;
// means the same as: a=a-7;

cout<<"the new value of a is: "<<a<<endl;
}

********************

// - the for cycle:

for(prog1; prog2; prog3)
{
  statements;
}

EX.:

int s=0;

for(int i=0; i<10; ++i)
{
  s+=i;
  cout<<"the value of s is: "<<s<<endl;
}