A simple C program: Printing a line of text

#include <stdio.h>

main()

{

printf(“hello, world\n”);

}

Program output:hello, world

More C programs

#include <stdio.h>

main()

{

printf(“My first program.\n”);

printf(“It is wonderful.”);

}

Program output:

My first program.

It is wonderful.

More C programs

#include <stdio.h>

main()

{

printf(“My first program.”);

printf(“It is wonderful.”);

}

Program output:

My first program.It is wonderful.

Printing characters

Source program:printf(“Welcome\nto\nCOMP 1180!\n”);

Program output:Welcome

to

COMP 1180!

You can use printf to print a string of characters;

but there are special cases:

• For double quote, use \”

• For single quote, use \’

• For backslash, use \\

• For newline, use \n

Formatted Output (integer,float,char,string)• Almost every C program start with the following:

#include <stdio.h>

for the access to the standard input/output library

• For the “printf” statement:printf(format-string, arg1, arg2, ...);

• Format-string tells the program how to print the arguments out

• Format-string contains two types of objects: ordinary characters and conversion specifications

• Each conversion specification begins with a % and ends with a conversion character and maybe have a minus sign, a number, and a period in between

Basic Printf Conversions

%d %i integer

%o octal (Base 8)

%x %X hexadecimal (Base 16)

%f floating point

%e %E floating point (exponent)

%g %G floating point (general format)

%c single character

%s character string

%% print a %

Examples on Formatted Printf Statementsint a = 5; int b = 10; 123456789012345

printf(“%d\n”, a); 5

printf(“%5d\n”, a); 5

printf(“%5d\n”, b); 10

printf(“%d %d\n”, a, b); 5 10

printf(“a = %d b = %3d\n”, a, b); a = 5 b = 10

float x = 33.3456789; 123456789012345

printf(“%f\n”, x); 33.345679

printf(“%e\n”, x); 3.33457e+01

printf(“%8.3f\n”, x); 33.346

x = 0.3334567;

printf(“%e\n”, x); 3.33457e-01

More Examples on Printf (strings)

printf(“%s”, “hello, world”); hello, world:

printf(“%10s”, “hello, world”); hello, world:

printf(“%.10s”, “hello, world”); hello, wor:

printf(“%-10s”, “hello, world”); hello, world:

printf(“%.15s”, “hello, world”); hello, world:

printf(“%-15s”, “hello, world”); hello, world :

printf(“%15.10s”, “hello, world”); hello, wor:

printf(“%-15.10s”, “hello, world”); hello, wor :

Formatted Input

• For “scanf” statements,scanf(format-string, addr1, addr2, ...);

• Examples:float f;

int lower, upper;

char ch;

scanf(“%f”, &fahr);

scanf(“%d%d”, &lower, &upper);

scanf(“%c”, ch);

ch = getchar(); get the next character from STDIN

putchar(ch); put the character to STDOUT