1. Notes About Boolean Expressions
No boolean type, so boolean expressions evaulate to 0(false) or 1(true).
x = (x > y); // is valid. It will set x to 0 or 1.
if (x) x++; // is valid. If x isn’t 0, it adds 1 to x.
!!5 // is equal to 1
For these reasons, try to use boolean expressions ONLY where they are meant to be used.

2. Short-Circuit Evaluation
AND (&&)
If the first component is false, the second is never evaluated
if (b !=0 && (a/b > 0)) … // If b is zero, we never try to divide by it
OR (||)
If the first component is true, the second is never evaluated
if (age >= 21 || fakeid == 1) … // If you are older than 21, you don’t need to check for the fake!

3. Block of Statements/ Empty Statement
A block of statements ({}) acts as a single statement for syntactic purposes, which is why we use a block for a part of an if statement
An empty statement is as follows: ; This is important because if you add a semicolon somewhere, it changes the interpretation of the statement
if (b !=0); value = a/b; // Here, the division happens even when b is 0…

4. #include <stdio.h>
int main() {
int roomlen, roomwid;
int desklen, deskwid;
printf("Enter the length and width of the room.\n");
scanf("%d%d",&roomlen, &roomwid);
printf("Enter the length and width of the desk.\n");
scanf("%d%d",&desklen, &deskwid);
if ((deskwid <= roomwid) && (desklen <= roomlen))
printf(“The desk will fit in the room.\n”);
else
printf(“The desk will not fit in the room.\n”);
return 0; }

5. Revision #1 //Adjust lengths and widths, if necessary
if (roomlen < roomwid) {
roomlen = roomwid;
roomwid = roomlen; }
if (desklen < deskwid) {
desklen = deskwid;
deskwid = desklen;
What’s WRONG with this solution?

6. Corrected Program
Add the following after the scanfs to the original program:
//Adjust lengths and widths, if necessary
if (roomlen < roomwid) {
temp = roomlen;
roomlen = roomwid;
roomwid = temp; }
if (desklen < deskwid) {
temp = desklen;
desklen = deskwid;
deskwid = temp;

7. Another Solution
if ((deskwid <= roomwid) && (desklen <= roomlen))
printf(“The desk will fit in the room.\n”);
else if ((deskwid<=roomlen) && (desklen<=roomwid))
else
printf(“The desk will not fit in the room.\n”);