String.Format C# - Everything You Need to Know

In this tutorial you will learn
  1. What is String.Format?
  2. How to use String.Fromat?
  3. Currency Formation
  4. DateTime Formation
  5. Decimal, Double, Float and Int Formation

String.Format converts the value according the Format specified by you. In this tutorial, you will learn all techniques to convert every type of value in the desired format.

Demo Program

Here, I am writing a demo program to make you clear how String.Format works. Here I have some decimal value and I will convert them into currency. The currency icon will be displayed according to your locale settings.

Programming Example

using System;

namespace StringFormat_Example
{
    public class Program
    {
        public static void Main(string[] args)
        {
            decimal coin=17.36m;
            Console.WriteLine(String.Format("{0:C}",coin));
        }
    }
}
Output
₹ 17.36
_

It is just a demo program and there is wide range of String.Format formation available. In this article I have tried to combine all Formation that will help you to learn entire aspect in one article.

In this Chapter you will learn

String.Format for Currency Conversion

Most of the time you need to display integer, double or number value into currency. You don’t need to write dozens line of code for it. Just let String.Format in action and customize value for it.

Format Description
{0:C} It displays the actual value with currency
{0:C4} It displays actual value along with 4 digit after point precision.
{0:C6} It displays actual value along with 6 digit after point precision.

Programming Example

using System;

namespace StringFormat_Currency
{
    public class Program
    {
        public static void Main(string[] args)
        {
            decimal dcoin=2398.87m;
            int icoin=2309;
            float fcoin=9283.65f;
            Console.WriteLine(String.Format("Convert Decimal {0:C}",dcoin));
            Console.WriteLine(String.Format("Convert Decimal {0:C4}",icoin));
            Console.WriteLine(String.Format("Convert Decimal {0:C6}",fcoin));
        }
    }
}
Output
Convert Decimal ₹ 2,398.87
Convert Decimal ₹ 2,309.0000
Convert Decimal ₹ 9,283.650000
_

String.Format for DateTime Conversion

This is the area where String.Format is widely used. A simple DateTime program doesn’t give formatted output. String.Format in C# helps you to display DateTime according to your need. You can apply following formation on DateTime.

Format Description
{0:yy} Displays Year in 2 Digits
{0:yyyy} Displays Year in 4 Digits
{0:MM} Displays Month. Use Capital ‘M’ for month because small m for minutes.
{0:dd} Displays Day Date
{0:dd-MM-yyyy} Displays date in dd-MM-YYYY format.
{0:hh:mm:ss} Displays Time in hh:mm:ss format.
{0:zz} Displays Current TimeZone
Always remember while formatting date
y for Years
M for months
d for date
h for hour
m for minutes
s for seconds
f for millisecond
z for timezone

Programming Example

using System;

namespace StringFormat_DateTime
{
    public class Program
    {
        public static void Main(string[] args)
        {
            DateTime dt=DateTime.Now;            

            //Start Formation
            Console.WriteLine(String.Format("Original Value :- {0}",dt));
            Console.WriteLine(String.Format("Display Year in 2 Digits :- {0:yy}",dt));
            Console.WriteLine(String.Format("Display Year in 4 Digits :- {0:yyyy}",dt));
            //Use Capital M for month. Small m displays minutes
            Console.WriteLine(String.Format("Display Year and Months :- {0:yyyy MM}",dt));
            Console.WriteLine(String.Format("Display date, month and  Year :- {0:dd MM yyyy}",dt));
            Console.WriteLine(String.Format("Display Time :- {0:hh:mm:ss}",dt));
           Console.WriteLine(String.Format("My Time Zone is :- {0:zz}",dt));
        }
    }
}
Output
Original Value :- 17/02/17 9:56:00 AM
Display Year in 2 Digits :- 17
Display Year in 4 Digits :- 2017
Display Year and Months :- 2017 02
Display date, month and Year :- 17 02 2017
Display Time :- 09:56:00
My Time Zone is :- +05
_

DateTimeFormatInfo

There are some defined standards in DateTimeFormatInfo that will help you to customize Date Time in the easiest way. Here is the list of Defined Standard for en-us culture.

Specifier Property Pattern (en-us culture)
t ShortTimePattern h:mm tt
d ShortDatePattern M/d/yyyy
T LongTimePattern h:mm:ss tt
D LongDatePattern dddd, MMMM dd, yyyy
f (combination of D and t) dddd, MMMM dd, yyyy h:mm tt
F FullDateTimePattern dddd, MMMM dd, yyyy h:mm:ss tt
g (combination of d and t) M/d/yyyy h:mm tt
G (combination of d and T) M/d/yyyy h:mm:ss tt
m,M MonthDayPattern MMMM dd
y, Y YearMonthPattern MMMM, yyyy
r, R RFC1123Pattern ddd, dd MMM yyyy HH':'mm':'ss 'GMT' (*)
s SortableDateTi­mePattern yyyy'-'MM'-'dd'T'HH':'mm':'ss (*)
u UniversalSorta­bleDateTimePat­tern yyyy'-'MM'-'dd HH':'mm':'ss'Z' (*)

Programming Example

using System;

namespace StringFormat_DateTimeFormatInfo
{
    public class Program
    {
        public static void Main(string[] args)
        {
            DateTime dt=DateTime.Now;            

            //Start Formation
            Console.WriteLine(String.Format("Short Time Pattern [t] : {0:t}",dt));
            Console.WriteLine(String.Format("Short Date Pattern [d] : {0:d}",dt));
            Console.WriteLine(String.Format("Long Time Pattern [T] : {0:T}",dt));
            Console.WriteLine(String.Format("Long Date Pattern [D] : {0:D}",dt));
            Console.WriteLine(String.Format("Combination of D and T [f] : {0:f}",dt));
            Console.WriteLine(String.Format("Full Date Time Pattern [F] : {0:F}",dt));
            Console.WriteLine(String.Format("Combination of d and t [g] : {0:g}",dt));
            Console.WriteLine(String.Format("Combination of d and T [G] : {0:G}",dt));
            Console.WriteLine(String.Format("Month Day Pattern [m or M] : {0:M}",dt));            
            Console.WriteLine(String.Format("Year Month Pattern [y or Y] : {0:Y}",dt));
            Console.WriteLine(String.Format("RFC1123Pattern [r or R] : {0:R}",dt));
            Console.WriteLine(String.Format("SortableDateTi­mePattern [s] : {0:s}",dt));
            Console.WriteLine(String.Format("UniversalSorta­bleDateTimePat­tern [u] : {0:u}",dt));
        }
    }
}
Output
Short Time Pattern [t] : 9:53 AM
Short Date Pattern [d] : 17/02/17
Long Time Pattern [T] : 9:53:09 AM
Long Date Pattern [D] : Friday 17 February 2017
Combination of D and T [f] : Friday 17 February 2017 9:53 AM
Full Date Time Pattern [F] : Friday 17 February 2017 9:53:09 AM
Combination of d and t [g] : 17/02/17 9:53 AM
Combination of d and T [G] : 17/02/17 9:53:09 AM
Month Day Pattern [m or M] : 17 February
Year Month Pattern [y or Y] : February 2017
RFC1123Pattern [r or R] : Fri, 17 Feb 2017 09:53:09 GMT
SortableDateTi­mePattern [s] : 2017-02-17T09:53:09
UniversalSorta­bleDateTimePat­tern [u] : 2017-02-17 09:53:09Z
_

String.Format for Double, Decimal, Float or Int

Several times you need to get customize output for Double, Decimal or Float value. Sometimes output in this datatype is too long after point precision and you just need to cut rest of the value after point precision. String.Format helps you lot in customizing Double, Decimal or Float value.

Formatting Table
Format Explain Value Output
{0} Original Value 83745.892 83745.892
{0:0.00} Two decimal places after point. 83745.892 83745.89
{0:0.##} Maximum Two decimal places after point 83745.892 83745.89
{0:00.00} Two digits before decimal point 5.892 05.892
{0:0,0.00} Thousands Separator 83745.892 83,745.89
{0:0.0} Point number conversion with zero 0.5 0.5
{0:#.0} Point number conversion without zero 0.5 .5
{0,10:0.0} Align Number with Spaces 120.5 “ 120.5”
{0,10:0.0} Align Number with Spaces 120.5 “120.5 Hello”
{0:###-##-####} Phone Number format 123456789 123-45-6789

Programming Example

using System;

namespace StringFormat_Double
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //Start Formation
            Console.WriteLine("Current Output : {0}", 83745.892);
            Console.WriteLine(string.Format("Two decimal places : {0:0.00}",83745.892));
            Console.WriteLine(string.Format("Three decimal places : {0:0.000}",83745.82));
            Console.WriteLine(string.Format("Maximum Two decimal places : {0:0.##}",83745.892));
            Console.WriteLine(string.Format("Two digits before decimal point : {0:00.00}",5.892));
            Console.WriteLine(string.Format("Thousands Separator : {0:0,0.00}",83745.892));
            Console.WriteLine(string.Format("Point number conversion with zero : {0:0.0}",0.5));
            Console.WriteLine(string.Format("Point number conversion without zero : {0:#.0}",0.5));
            Console.WriteLine(string.Format("Align Number with Spaces : {0,10:0.0}",120.5));
            Console.WriteLine(string.Format("Align Number with Spaces : {0,-10:0.0} Hello",120.5));
           Console.WriteLine(string.Format("Phone Number format {0:###-##-####}",123456789));
        }
    }
}
Output
Current Output : 83745.892
Two decimal places : 83745.89
Three decimal places : 83745.820
Maximum Two decimal places : 83745.89
Two digits before decimal point : 05.89
Thousands Separator : 83,745.89
Point number conversion with zero : 0.5
Point number conversion without zero : .5
Align Number with Spaces : 120.5
Align Number with Spaces : 120.5 Hello
Phone Number format 123-45-6789
_

Summary

In this tutorial, I have tried to explain String.Format widely with suitable and realistic programming example. It is very important for every programmer to know how to use String.Format in their program. It makes the user experience more realistic and valuable.

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