C Comments
Comments in C
Comments are notes for humans. They help explain code and make it easier to read.
They can also be used to temporarily "disable" code while testing.
Comments can be single-line or multi-line.
Remember: Comments are ignored by the compiler, so they do not affect your program's output.
Single-line Comments
Single-line comments start with two forward slashes (//).
Any text between // and the end of the line is ignored by the compiler.
This example uses a single-line comment before a line of code:
This example uses a single-line comment at the end of a line of code:
You can also use // to disable a single line of code:
Multi-line Comments
Multi-line comments start with /* and end with */.
Any text between /* and */ will be ignored by the compiler:
Example
/* The code below will print the words Hello World!
to the screen, and it is
amazing */
printf("Hello World!");
Try it Yourself »
Single or multi-line comments?
It is up to you which you want to use. Normally, we use // for short comments and /* */ for longer comments.
Good to know: Before C99 (released in 1999), you could only use multi-line comments in C.
