Jan 23, 2010 Okay, if I ever use the printf or cont function, the window will quickly close itself out. I know how to fix this when I am using the cont function (by putting cin.ignore right after it), but how do I fix this when using the printf function. Sep 17, 2009 Se suele usar antes de un printf, para poner el texto en una cierta parte de la pantalla. El comando gotoxy no corre, me dice que hay un problema, uso el DEV-C. The printf function in C is used to write a formatted string to stdout.

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Description

The C library function int printf(const char *format, ...) sends formatted output to stdout.

Declaration

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Following is the declaration for printf() function.

Parameters

  • format − This is the string that contains the text to be written to stdout. It can optionally contain embedded format tags that are replaced by the values specified in subsequent additional arguments and formatted as requested. Format tags prototype is %[flags][width][.precision][length]specifier, which is explained below −

Sr.No.Specifier & Output
1

c

Character

2

d or i

Signed decimal integer

3

e

Scientific notation (mantissa/exponent) using e character

4

E

Scientific notation (mantissa/exponent) using E character

5

f

Decimal floating point

6

g

Uses the shorter of %e or %f

7

G

Uses the shorter of %E or %f

8

o

Signed octal

9

s

String of characters

10

u

Unsigned decimal integer

11

x

Unsigned hexadecimal integer

12

X

Unsigned hexadecimal integer (capital letters)

13

p

Pointer address

14

n

Nothing printed

15

%

Character

Sr.No.Flags & Description
1

-

Left-justify within the given field width; Right justification is the default (see width sub-specifier).

2

+

Forces to precede the result with a plus or minus sign (+ or -) even for positive numbers. By default, only negative numbers are preceded with a -ve sign.

3

(space)

If no sign is going to be written, a blank space is inserted before the value.

4

#

Used with o, x or X specifiers the value is preceded with 0, 0x or 0X respectively for values different than zero. Used with e, E and f, it forces the written output to contain a decimal point even if no digits would follow. By default, if no digits follow, no decimal point is written. Used with g or G the result is the same as with e or E but trailing zeros are not removed.

5

0

Left-pads the number with zeroes (0) instead of spaces, where padding is specified (see width sub-specifier).

Sr.No.Width & Description
1

(number)

Minimum number of characters to be printed. If the value to be printed is shorter than this number, the result is padded with blank spaces. The value is not truncated even if the result is larger.

2

*

The width is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

Sr.No..precision & Description
1

.number

For integer specifiers (d, i, o, u, x, X) − precision specifies the minimum number of digits to be written. If the value to be written is shorter than this number, the result is padded with leading zeros. The value is not truncated even if the result is longer. A precision of 0 means that no character is written for the value 0. For e, E and f specifiers − this is the number of digits to be printed after the decimal point. For g and G specifiers − This is the maximum number of significant digits to be printed. For s − this is the maximum number of characters to be printed. By default all characters are printed until the ending null character is encountered. For c type − it has no effect. When no precision is specified, the default is 1. If the period is specified without an explicit value for precision, 0 is assumed.

2

.*

The precision is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

Sr.No.Length & Description
1

h

The argument is interpreted as a short int or unsigned short int (only applies to integer specifiers: i, d, o, u, x and X).

2

l

The argument is interpreted as a long int or unsigned long int for integer specifiers (i, d, o, u, x and X), and as a wide character or wide character string for specifiers c and s.

3

L

The argument is interpreted as a long double (only applies to floating point specifiers: e, E, f, g and G).

  • additional arguments − Depending on the format string, the function may expect a sequence of additional arguments, each containing one value to be inserted instead of each %-tag specified in the format parameter (if any). There should be the same number of these arguments as the number of %-tags that expect a value.

Return Value

If successful, the total number of characters written is returned. On failure, a negative number is returned.

Example

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The following example shows the usage of printf() function.

Let us compile and run the above program to produce the following result −

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Unlike for and while loops, which test the loop condition at the top of the loop, the do...while loop checks its condition at the bottom of the loop.

A do...while loop is similar to a while loop, except that a do...while loop is guaranteed to execute at least one time.

Syntax

The syntax of a do...while loop in C++ is −

Notice that the conditional expression appears at the end of the loop, so the statement(s) in the loop execute once before the condition is tested.

If the condition is true, the flow of control jumps back up to do, and the statement(s) in the loop execute again. This process repeats until the given condition becomes false.

Flow Diagram

Example

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When the above code is compiled and executed, it produces the following result −

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