- The scanf() function
is used to read in values of
all built-in data types
in C.
- Syntax of the printf()
function:
scanf ( " format string " , &var1, &var2, ..... );Very important note:
- The & character is
the "reference" operator
of the C programming language
- The expression
&x means:
the address of the variable x
- You must pass the
address of a variable to the
scanf() function for
reading operations.
We will discuss the & operator in more details later....
- The & character is
the "reference" operator
of the C programming language
- Format string:
- The format string in the scanf() function contains formatting characters that instruct the C compiler to read in a value and store it in the given representation (encoding)
- Commonly used formatting characters:
Formatting character Meaning %d Print the (next) value as a signed integer value %u Print the (next) value as a unsigned integer value %ld Print the (next) value as a long signed integer value %lu Print the (next) value as a long unsigned integer value %f Print the (next) value as a floating point value %lf Print the (next) value as a double precision floating point value %c Print the (next) value as a character (i.e., used the ASCII code) %s Print the (next) value as a string (will be explained much later)
- Example:
int main( int argc, char* argv[] ) { int i; float x; printf( "Enter an integer value:"); scanf( "%d", &i ); printf( "i = %d\n", i); printf( "Enter a floating point value:"); scanf( "%f", &x ); printf( "x = %f\n", x); }Sample Output:
Enter an integer value:56 i = 56 Enter a floating point value:3.14 x = 3.140000
- Example Program:
(Demo above code)
- Prog file: click here
How to run the program:
- Right click on link and
save in a scratch directory
- To compile: gcc scanf1.c
- To run: ./a.out
- Fact:
- scanf()
return the number of items
read
- scanf()
return the value −1
when you type
control-D
at the keyboard
(The character control-D represents end-of-file (EOF) in UNIX)
- scanf()
return the number of items
read
- How to read a serie of
integers until
EOF:
int main( int argc, char* argv[] ) { int i; printf( "Enter an integer value: "); while ( scanf( "%d", &i ) != EOF ) { printf( "i = %d\n", i); printf( "Enter another integer value (type ^D to end): "); } printf( "\nDONE !\n" ); }
- Example Program:
(Demo above code)
- Prog file: click here
How to run the program:
- Right click on link and
save in a scratch directory
- To compile: gcc scanf2.c
- To run: ./a.out