I have a doubt about the for loop, that is, I have a for statement and I have to get the result that the machine gave. I have this:
for(x=2,Y=1;X < 11;x++)y+=x++
I know that the variable X starts at 2 and Y at 1. I know that while X is less than 11 it cycles. Here's my problem. Which cycle. I make x + 1 until X has the value of 11? Or I make the rule out that is:
x=x+1
y=y+x
Thank you
To understand better, follow your code with some instructions for debug :
int x;
int y;
for( x=2, y=1; x<11; x++ ) {
printf("antes x = %d, y= %d \n", x, y );
y += x++;
printf("depois x = %d, y= %d \n", x, y );
}
printf("final x = %d, y= %d \n", x, y );
Here's the result:
antes x = 2, y= 1
depois x = 3, y= 3
antes x = 4, y= 3
depois x = 5, y= 7
antes x = 6, y= 7
depois x = 7, y= 13
antes x = 8, y= 13
depois x = 9, y= 21
antes x = 10, y= 21
depois x = 11, y= 31
final x = 12, y= 31
See working at IDEONE .
Briefly, the order of execution is this:
for( x=2,y=1; X < 11; x++ ) y += x++
---1--- ---2-- -5- --3- -4-
After the 5th step, return to the 1st, until the condition of the 2nd give false .
All for can be replaced by while .
You may find the syntax of while more intuitive: -)
for (initialization; condition; increment) body;
for (initialization; condition; increment) {body};
initialization;
while (condition) {
body;
increment;
}
In your specific case, the code is
// for (x = 2, y = 1; x < 11; x++) y += x++;
x = 2; y = 1;
while (x < 11) {
y += x++;
x++;
}
Where it is well seen that x will be incremented 2 times each time within the cycle.