C language: if() with no else(): using braces fails

Question

I\'m confused on need for braces after IF() expression. When using IF(){...}ELSE{...} I\'m used to using braces around both IF and ELSE blocks. But when I use no ELSE block it

Answer 1

A single statement follows the if. If you need multiple statements, they must be combined into a single compound statement.

if (input(3) == 1)
    high(14);
pause(50);
low(14);
pause(50);

executes both pause functions and low regardless of what input returns. Where you put the newlines does not affect how C parses the code. You need braces to combine the 4 function calls into a single compound statement:

if (input(3) == 1) {
    high(14);
    pause(50);
    low(14);
    pause(50);
}

The absence or presence of an else clause does not change anything, except that

if (input(3) == 1)
    high(14);
pause(50);
else ...

would result in an error, since the else is not joined to any if statement; the if concludes with the single statement high(14), and the pause(50) is a separate statement altogether, so the else is out of place.