C# How to Convert String to Float with Examples

In C#, convert a string to a float using float.Parse(stringValue) or safely with float.TryParse(stringValue, out float result).

Examples

Input"3.14"

Output3.14

Input"-0.001"

Output-0.001

Input"abc"

OutputConversion failed (TryParse returns false)

How to Think About It

To convert a string to a float, first consider if the string is always a valid number. If yes, use float.Parse which throws an error if invalid. If not sure, use float.TryParse which returns true or false and avoids errors.

Algorithm

1

Get the input string.

2

Try to convert the string to a float using a safe method.

3

If conversion succeeds, return the float value.

4

If conversion fails, handle the error or return a default value.

Code

csharp

using System;

class Program {
    static void Main() {
        string input = "3.14";
        if (float.TryParse(input, out float number)) {
            Console.WriteLine(number);
        } else {
            Console.WriteLine("Conversion failed.");
        }
    }
}

Output

3.14

Dry Run

Let's trace converting the string "3.14" to float using TryParse.

1

Input string

input = "3.14"

2

TryParse conversion

float.TryParse("3.14", out number) returns true and number = 3.14

3

Output result

Print 3.14

Input String	TryParse Result	Output Number
3.14	true	3.14

Why This Works

Step 1: Using float.Parse

float.Parse converts a valid numeric string to float but throws an exception if the string is invalid.

Step 2: Using float.TryParse

float.TryParse attempts conversion and returns a boolean indicating success, avoiding exceptions.

Step 3: Output handling

If conversion succeeds, the float value is used; otherwise, you can handle failure gracefully.

Alternative Approaches

Using float.Parse with try-catch

csharp

using System;

class Program {
    static void Main() {
        string input = "3.14";
        try {
            float number = float.Parse(input);
            Console.WriteLine(number);
        } catch (FormatException) {
            Console.WriteLine("Invalid input string.");
        }
    }
}

This method throws an exception on invalid input, so you must handle errors with try-catch.

Using Convert.ToSingle

csharp

using System;

class Program {
    static void Main() {
        string input = "3.14";
        try {
            float number = Convert.ToSingle(input);
            Console.WriteLine(number);
        } catch (FormatException) {
            Console.WriteLine("Invalid input string.");
        }
    }
}

Convert.ToSingle also converts string to float but throws exceptions on invalid input.

Complexity: O(1) time, O(1) space

Time Complexity

Conversion is a simple parsing operation that runs in constant time.

Space Complexity

Only a few variables are used, so space is constant.

Which Approach is Fastest?

float.Parse and float.TryParse have similar speed; TryParse is safer for unknown input.

Approach	Time	Space	Best For
float.Parse	O(1)	O(1)	Known valid strings, simple code
float.TryParse	O(1)	O(1)	Unknown input, safe conversion
Convert.ToSingle	O(1)	O(1)	Similar to Parse, with exception handling