Formatting data via printf() - C++ Language Basics

C++ examples for Language Basics:Console

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Description

Formatting data via printf() 

int printf(const char *fmt , arg-list)
Code Format
%c Character.
%d Signed decimal integers.
%i Signed decimal integers.
%e Scientific notation (lowercase e).
%E Scientific notation (uppercase E).
%f Decimal floating point.
%g Uses %e or %f, whichever is shorter (if %e, uses lowercase e).
%G Uses %E or %f, whichever is shorter (if %E, uses uppercase E).
%o Unsigned octal.
%s Null-terminated string.
%u Unsigned decimal integers.
%x Unsigned hexadecimal (lowercase letters).
%X Unsigned hexadecimal (uppercase letters).
%p Displays an address.
%n The associated argument shall be a pointer to an integer, into which is placed the number of characters written so far.
%% Prints a % sign.

Format Floating-Point Values

The %f format specifier displays a double argument in floating-point format.

The %e and %E specifiers tell printf( ) to display a double argument in scientific notation.

Numbers represented in scientific notation take this general form: 

x.dddddE+/-yy

The following program shows several examples of printf().

Demo Code

#include <cstdio>
#include <cmath>
using namespace std;
int main()/*from  www  .j  a  v a  2  s  . c o m*/
{
   int x = 10;
   double val = 568.345;
   // It is not necessary for a call to printf() to include
   // format specifiers or additional arguments.
   printf("This is output to the console.\n");
   // Display numeric values.
   printf("This is x and val: %d %f\n\n", x, val);
   printf("This is x in uppercase hex: %X\n", x);
   printf("Mix data %d into %f the format string.\n\n", 19, 234.3);
   // Specify various precisions, widths, and sign flags.
   printf("Here is val in various precisions, widths, and sign flags: \n");
   printf("|%10.2f|%+12.4f|% 12.3f|%f|\n", val, val, val, val);
   printf("|%10.2f|%+12.4f|% 12.3f|%f|\n", -val, -val, -val, -val);
   printf("\n");
   // Display column of numbers, right-justified.
   printf("Right-justify numbers.\n");
   for(int i = 1; i < 11; ++i)
      printf("%2d %8.2f\n", i, sqrt(double(i)));
   printf("\n");
   // Now, left-justify some strings in a 16-character field.
   // Right-justify the quantities.
   printf("%-16s Quantity: %3d\n", "Hammers", 12);
   printf("%-16s Quantity: %3d\n", "Pliers", 6);
   printf("%-16s Quantity: %3d\n", "Screwdrivers", 19);
   return 0;
}

Result


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