C Programming Tutorial
In the C Programming Language, the printf function writes a formatted string to the stdout stream.
Syntax
The syntax for the printf function in the C Language is:
int printf(const char *format, ...);
Parameters or Arguments
format
Describes the output as well as provides a placeholder to insert the formatted string. Here are a few examples:
Format | Explanation | Example |
---|---|---|
%d | Display an integer | 10 |
%f | Displays a floating-point number in fixed decimal format | 10.500000 |
%.1f | Displays a floating-point number with 1 digit after the decimal | 10.5 |
%e | Display a floating-point number in exponential (scientific notation) | 1.050000e+01 |
%g | Display a floating-point number in either fixed decimal or exponential format depending on the size of the number (will not display trailing zeros) | 10.5 |
Returns
The printf function returns the number of characters that was written. If an error occurs, it will return a negative value.
Required Header
In the C Language, the required header for the printf function is:
#include <stdio.h>
Applies To
In the C Language, the printf function can be used in the following versions:
- ANSI/ISO 9899-1990
printf Example
Here are some examples that use the printf function:
printf("%s\n","c programming");
Result: c programming printf("%s is over %d years old.\n","c programming",10);
Result: c programming is over 10 years old. printf("%s is over %d years old and pages load in %f seconds.\n","c programming",10,1.4);
Result: c programming is over 10 years old and pages load in 1.400000 seconds. printf("%s is over %d years old and pages load in %.1f seconds.\n","c programming",10,1.4); Result: c programming is over 10 years old and pages load in 1.8 seconds.
Example - Program Code
Let's look at an example to see how you would use the printf function in a C program:
/* Example using printf */ #include <stdio.h> int main(int argc, const char * argv[]) { /* Define variables */ int age = 10; float load = 1.4; /* Display the results using the appropriate format strings for each variable */ printf("c programming is over %d years old and pages load in %.1f seconds.\n", age, load); return 0; }
This C program would print "c programming is over 10 years old and pages load in 1.8 seconds."