##
**Introduction to Formatting Numbers **

Let us say that your program is calculating a number in decimal and you needed to print out leading zeros to it, how would you do it? If there is no need for formatting, you can just use the print command.

```
``````
my $a = 10.003403;
print "$a";
```

This gives you the value of

In Perl, you can use the

Say in the example, this is a price of an item. You can't display the cost of an item as $10.003403. You need to truncate the number to two decimal places.

When I was beginning to write in Perl, I did not know this function so what I did was to split the number then substring the decimal numbers to 2 and then concatenate them:

*. But let us say that you need to limit the decimal point to 2 decimal digits, how would you do that?***$a**In Perl, you can use the

*function. You can also use***printf***to set to result to a variable. The***sprintf***function allows you to format a number the way that you would want to.***printf**Say in the example, this is a price of an item. You can't display the cost of an item as $10.003403. You need to truncate the number to two decimal places.

When I was beginning to write in Perl, I did not know this function so what I did was to split the number then substring the decimal numbers to 2 and then concatenate them:

`my @val = split('.', $a);`

`$a = "$val[0]." . substr($val[1], 0, 2);`

This did the job but quite bulky and inefficient. Little did I know that Perl has a function to simplify this:

```
````$a = sprintf("%0.2f", $a);`

With just one statement, we are able to format the variable to what we wanted.

##
**sprintf Conversion Format**

If we have

```
``````
````$a = -10.3490;`

and the

**sprintf**format is as specified in the table, the result will be as shown in the table.

The

**sprintf**format can be used to convert an integer to:

Conversion Type | Format | Result |

A percent sign | %% | % |

Convert the integer to character | %c | _Ă˘++++¦ |

Convert the integer to a string | %s | -10.349 |

Display as a signed integer | %d | -10 |

Display as unsigned decimal integer | %u | 4294967286 |

Display as an unsigned octal integer | %o | 37777777766 |

Display as an unsigned hexadecimal integer | %x | fffffff6 |

Same as above but letters are displayed in caps | %X | FFFFFFF6 |

Display as a scientific floating point number | %e | -1.034900e+001 |

Same as above but letters are displayed in caps | %E | -1.034900E+001 |

Display number with decimal point | %f | -10.349000 |

Display the integer either in %e or %f format | %g | -10.349 |

Same as above but cletters are displayed in caps | %G | -10.349 |

Display in binary | %b | 11111111111111111111111111110110 |

Display the value's address in hexadecimal | %p | 1765764 |

The above conversions still do not allow us to format the integer. To show an example, we will use these flags with the %d conversion format. To format the integer, you need to specify these flags:

Description | Flag | Format | Result |

Length of the formatted number | any number | %10f | -10.349000 |

Add space to a positive number | space | % f | -10.349000 |

Add a positive sign to a positive number | + | %+f | -10.349000 |

Left justify | - | %-f | -10.349000 |

pad zeroes to right justify | 0 | %0f | -10 |

specify number of decimal digits | .number | %.2f | -10.35 |

You can also mix these flags together. So if you want to have two decimal places and limit the length of the number to 10 digits (including the decimal numbers), you can do this:

```
````sprintf("%10.2f", $a);`

The result will be a number with two decimal places padded with spaces.

`-10.35`

If you want to pad this number with zeroes, you can do this:

```
```` sprintf("%010.2f", $a);`

```
```

The result will be:

`-000010.35`

For more information on the

**sprintf**and**printf**functions, read the**perlfunc**documentation
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