C# string to int conversion tutorial

last modified July 5, 2023

C# string to int tutorial shows how to convert strings to integers. We can use the methods of the Convert class such as Convert.ToInt32, Int32.Parse, and Int32.TryParse to do the conversions.

C# string to int conversion

String to integer conversion is a type conversion or type casting, where an entity of string data type is changed into integer one. This type of conversion is very common because we receive values from forms, command line parameters, or databases as strings, even if the values are integers.

The Convert.ToInt32 converts an object to an integer and returns 0 if the value was null. The Int32.Parse and Int32.TryParse methods also convert strings to integers. The difference between them is that Int32.Parse throws exceptions if the parsing operation fails while Int32.TryParse returns false.

There are equivalent methods for other numeric types; for instance Int64.TryParse or Double.Parse.

C# string to int with Convert.ToInt32

The Convert class contains methods for converting base data type to another base data type.

Numeric type	Method
decimal	ToDecimal
float	ToSingle
double	ToDouble
showrt	ToInt16
int	ToInt32
long	ToInt64
ushort	ToUInt16
uint	ToUInt32
ulong	ToUInt64

The table lists methods to convert strings to various integer numeric types. The Convert.ToInt32 converts a specified value to a 32-bit signed integer.

Program.cs

string applesInBasket = "12";
string baskets = "4";

int total = Convert.ToInt32(applesInBasket) * Convert.ToInt32(baskets);

string msg = $"There are total of {total} apples";
Console.WriteLine(msg);

In the example, we multiply two integer values that we have initially as strings.

int total = Convert.ToInt32(applesInBasket) * Convert.ToInt32(baskets);

We convert the strings and compute the expression.

$ dotnet run
There are total of 48 apples

C# string to int with Int32.Parse

The Int32.Parse method converts the string representation of a number to its 32-bit signed integer equivalent. It throws an exception if the conversion fails.

Program.cs

string val = "23423453263456345";

try
{
    int num = Int32.Parse(val);

    Console.WriteLine($"Converted '{val}' to {num}.");
}
catch (FormatException)
{
    Console.WriteLine($"Unable to convert '{val}'.");
}
catch (OverflowException)
{
    Console.WriteLine($"'{val}' is out of range of the Int32 type.");
}

In the example, we parse a very large number represented as a string. Since the value cannot be converted to an integer, the OverflowException is thrown.

$ dotnet run
'23423453263456345' is out of range of the Int32 type.

C# string to int with Int32.TryParse

The Int32.TryParse method converts the string representation of a number to its 32-bit signed integer equivalent. A boolean return value indicates whether the operation succeeded. The integer value is passed to the second result parameter of the method.

Program.cs

string val = "2342";

if (Int32.TryParse(val, out int j))
{
    Console.WriteLine(j);
} else {

    Console.WriteLine("String could not be parsed.");
}

The example converts a string with the Int32.TryPars method. The if condition checks for a return value of the method.

Source

Strings and string literals

In this article we have shown how to perform string to int conversions in C#.

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