Using printf for output in C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the printf function in C?

The printf function is used to display text and variables on the screen (standard output). It helps communicate results or messages to the user.

beginner

How do you print a simple text message using printf?

Use printf("Your message here\n"); The \n adds a new line after the message.

beginner

What does the format specifier %d do in printf?

It tells printf to print an integer (whole number) value.

beginner

How do you print a variable value using printf?

Include a format specifier in the string and pass the variable after the string. Example: int x = 5; printf("Value: %d\n", x);

beginner

What happens if you forget to include \n at the end of a printf message?

The output stays on the same line, so the next output will continue right after it, which can make the text hard to read.

Which printf statement correctly prints the integer variable num?

A printf("%d", num);

B printf("%s", num);

C printf("num");

D printf(num);

Use %d to print an integer variable. %s is for strings, and printing the variable name or variable directly without format specifier is incorrect.

What does the \n character do in a printf string?

A Ends the program

B Prints a backslash

C Prints the letter n

D Starts a new line

\n moves the cursor to the next line, so the next output appears below.

How would you print the text "Hello, World!" exactly as is using printf?

A printf("Hello, World!\n");

B printf(Hello, World!);

C printf("Hello, World!");

D printf(%s, "Hello, World!");

Plain text must be enclosed in double quotes inside printf(). No format specifier is needed. This prints exactly "Hello, World!" without a trailing newline.

Which format specifier is used to print a floating-point number with printf?

A %c

B %f

C %d

D %s

%f is used for floating-point numbers, %d for integers, %c for characters, and %s for strings.

What will this code print? printf("%d %d", 3);

A Undefined behavior or garbage value

B 3 3

C 3

D Error: missing argument

Two %d specifiers need two integer arguments. Missing one causes unpredictable output.

Explain how to use printf to print a message and a variable value in C.

Think about how you combine text and variable values in one print statement.

What are some common format specifiers used with printf and what do they print?

Remember the type of data you want to show on screen.