for() loops are used to repeat a block of code a certain amount of times

for() loops have a fixed format

for(first; second; third){code block}

The first expression is executed once at the start of the statement. The second expression must evaluate to a boolean and is evaluated before every loop. The third expression is executed after every loop.

The following is an example of how a for() loop can be used

for(int i = 10; i >= 0; i--){
    fprintf(stdout, "T minus %d\n", i);
}
fprintf(stdout, "BLAST OFF!\n");

while() loops are used to repeat a block of code until a certain condition is no longer met

The format for a while loop is as follows:

while(expression){code block}

The expression within parentheses will run every loop before the code block and is evaluated as a boolean

The code block will run only if the expression within the parentheses evaluates to true

signed int value = 7;
while(value < 1000){
    fprintf(stdout, "value is %d\n", value);
    value = value * 2 + 3;
}

The loop in this code runs 7 times, outputting 7, 17, 37, 77, 157, 317, and 637; stopping before printing 1277

while() loops are best used when the amount of times a block of code is intended to run is not explicit or simple to calculate

do-while loops are used to repeat a block of code until a certain condition is no longer met

The only difference between a do-while loop and a while() loop is that the block of code in a do-while loop is run unconditionally initially

The format of a do-while loop is as follows:

do{code block}
while(expression);

The expression within parentheses will run every loop after the code block and is evaluated as a boolean

The code block will run only again if the expression within the parentheses evaluates to true

signed int value = 0;
do{
    fprintf(stdout, "value is %d\n", value);
    value = value * 2 + 3;
}
while(value > 0 && value < 1000);

This code prints value if it is between 0 and 1000 exclusive. However, value is printed while it is 0 because it was before the while() condition