For vs while loops

[numblocke]

I'm still quite a noob, and I've been reading a bit on learncpp.com and just completed a semester of C++ in college and I'm a bit confused about the specific advantages of a for loop over a while loop.

I understand what you have 3 parameters in the head of a loop, and so far the structure that we've been using has been something like this.

for (int i=0; i<=25; i++){
//for statements
}

Whereas I can do the exact same thing with a while loop with an initial statement:

int i=0
while (i<=25){
//statements
i++;
}

For some reason my brain really enjoys thinking in terms of while rather than for, is there really any large advantage for for's? If so can you show an example??

Thanks!

[Tamao]

Hello.

I only use while loops when i have conditions like:

bool condition = false;
while(!condition)
{

}

since you can't use boolean conditions in a for loop like this.
so while or do while has an advantage over for when it comes to other conditions than integers.

esle they are about the same.

[qtpan]

In "for loop",eventhough your conditions were met it will still do the loop. While in "while loop",once it became false i t will stop the loop,try binary search to see what i mean.

[guestgulkan]

@Tamao

since you can't use boolean conditions in a for loop like this.

What do you mean by that??


@qtpan

In "for loop",eventhough your conditions were met it will still do the loop. While in "while loop",once it became false i t will stop the loop,

Can you explain this please.....

[Vexer]

For loops must use a comparison like so:

var > 1

They cannot accept Boolean values(true or false).

While loops can accept Boolean values:

!var

For loops are great when you need to iterate a certain number of times.
While loops are great when you need to loop until a certain condition becomes false.

In "for loop",eventhough your conditions were met it will still do the loop. While in "while loop",once it became false i t will stop the loop,

This is not correct. Once the condition in a for loop becomes false, the loop will stop.

[AngelHoof]

I like to compare them by readability, and when it comes to usage of "for" vs "while", like many others i use while-loops for simpler stuff, and for-loops for the little more complex stuff. Sometimes a for-loop can make a complex loop much easier to read, in comparison to a while loop.

[Tamao]

@guestgulkan

What do you mean by that??

I mean that you can't stop a for loop with a boolean condition example:

for() // my for loop
if bool variable b is true
then stop the for loop 

it will continue until the loopcounter has met the condition

[blackcoder41]

Vexer wrote:

For loops must use a comparison like so:


var > 1


They cannot accept Boolean values(true or false).

While loops can accept Boolean values:


!var

For loop does accept boolean type. Conditional statements return boolean type anyway.

#include <iostream>

using namespace std;

int main()
{
    for(int i=1; true; i++) {
        cout << i << endl;
        if(i==10) break;
    }
    return 0;
}

[Vexer]

Thanks for the correction.

[guestgulkan]

Tamao wrote:

@guestgulkan

What do you mean by that??


I mean that you can't stop a for loop with a boolean condition example:

for() // my for loop
if bool variable b is true
then stop the for loop



it will continue until the loopcounter has met the condition

You are incorrect:
It is this part here (conditional_check):

for (initialisation; conditional_check; loop_expression)

that determines whether the loop continues or not.
Anything that will give a true/false result will suffice. Same as a while loop

[RedX]

Another advantage of for loops is the scope of the counter

for(int i;;){
//i only visible and valid here
}

int i;
while(){
//i valid here
}

//and here 

[Dufresne]

Everything , which can be done with while loop, can also be done with for loop.Moreover , with for loop, you use single line for all stuff.

Like
for( i = 0 , j = 20 ; i <= j ; i++ , j--) ;
If you decide to use while loop

i=0 ;
j =20 ;
while( i <= j )
{
   i++;
   j--;
}

I always prefer for loop.

[neeko]

As Dufresene has already pointed at, while and for loops are virtually identical in their operations. Logically, a while loop may be more appropriate over a for loop, however. For instance, lets say you are looping user input and are looping until char continue = 'n', you could write it in two ways

for(;continue != 'n';)

or

while(continue != 'n')

From a readability stand point, I'd prefer the while loop, but again they both will work just fine.