# Convert octal string to an integer number in C#

C# | Convert octal string to an integer: Here, we are going to learn how to convert a given string that contains an octal number in an integer number?
Submitted by IncludeHelp, on February 09, 2019

Given an octal string and we have to convert it into an integer number.

## Converting from octal string to integer

Let suppose you have a string "30071" which is an octal value of integer 12345, but this value is in string format, and you want to its integer (number) value.

To convert an octal string to an integer number – we use Convert.ToInt32() method.

Syntax:

```    Convert.ToInt32(input_string, Input_base);
```

Here,

• input_string is the input containing octal number in string format.
• input_base is the base of the input value – for an octal value it will be 8.

Example:

```    Input: "30071"
Function call:
Convert.ToInt32(input, 8);
Output:
12345

Input: "3007A" //not 'A' is not an octal number digit
Function call:
Convert.ToInt32(input, 8);
Output:
Exception
```

Code:

```using System;
using System.Text;

namespace Test
{
class Program
{
static void Main(string[] args)
{
//octal number as string
string input = "30071";
int output = 0;
//converting to integer
output = Convert.ToInt32(input, 8);
//printing the value
Console.WriteLine("Integer number: " + output);

//hit ENTER to exit
}
}
}
```

Output

```    Integer number: 12345
```

Example with Exception handling

Code:

```using System;
using System.Text;

namespace ConsoleApplication3
{
class Program
{
static void Main(string[] args)
{
string input = "";
int output = 0;
try
{
//input string
Console.Write("Enter an octal number: ");

//converting to integer
output = Convert.ToInt32(input, 8);

Console.WriteLine("Integer number: " + output);
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}

//hit ENTER to exit
}
}
}
```

Output

```First run with valid input:
Enter an octal number: 30071
Integer number: 12345

Second run with invalid input:
Enter an octal number: 3007A
System.FormatException: Additional non-parsable characters are at the end of the
string.
at System.ParseNumbers.StringToInt(String s, Int32 radix, Int32 flags, Int32*
currPos)
at System.Convert.ToInt32(String value, Int32 fromBase)
at ConsoleApplication3.Program.Main(String[] args) in F:\Ankur\SerialPort\Con
soleApplication3\ConsoleApplication3\Program.cs:line 19
```

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