Asp Classic Vbscript

Understanding the Key Differences Between Int() and CInt() in ASP/VBScript

When working with numbers in ASP/VBScript, it’s common to need to convert or manipulate numerical data. Two functions that often come up in this context are Int() and CInt(). Although they might seem similar at first glance, they serve different purposes and have distinct behaviors. In this blog post, we’ll explore the differences between Int() and CInt(), helping you understand when to use each.

Overview of the Functions

Int()

  • Purpose: The Int() function returns the integer part of a specified number, discarding any fractional component.

  • How It Works:

    • If you pass a positive number to Int(), it simply removes the decimal portion. For example, Int(3.9) would return 3.
    • For negative numbers, Int() behaves differently as it always rounds down towards the next lower integer. So, Int(-2.3) returns -3.

CInt()

  • Purpose: The CInt() function converts an expression to type Integer. Unlike Int(), it rounds the number to the nearest whole number.

  • How It Works:

    • For positive decimal values, CInt() rounds to the nearest integer. For instance, CInt(3.6) rounds up to 4, while CInt(3.4) rounds down to 3.
    • When dealing with exactly .5 values, CInt() follows the “round to nearest even” rule, meaning:
      • CInt(0.5) returns 0, and
      • CInt(1.5) returns 2.

When to Use Each Function

Choosing between Int() and CInt() can greatly impact the outcome of your program. Here are some guidelines:

  • Use Int() when:

    • You need the integer portion of a number and want to disregard any decimals completely.
    • You are working with negative numbers and want to round down.

  • Use CInt() when:

    • You need to perform rounding and want the nearest whole number.
    • You want to convert expressions to integer values, where standard rounding rules apply.

Examples to Illustrate the Differences

  1. Using Int()

    Dim number1, result1
number1 = 5.7
result1 = Int(number1) ' result1 will be 5

  2. Using CInt()

    Dim number2, result2
number2 = 5.7
result2 = CInt(number2) ' result2 will be 6

  3. Negative Numbers

    Dim number3, result3Int, result3CInt
number3 = -5.3
result3Int = Int(number3) ' result3Int will be -6
result3CInt = CInt(number3) ' result3CInt will be -5

Conclusion

Understanding the differences between Int() and CInt() is crucial for effective programming in ASP/VBScript. Whether you’re dealing with positive numbers or negative values, knowing when to use each function can help you manage numerical data more accurately.

For further reading on these functions, check out the official documentation on Int() and CInt(). Also, for a deeper understanding, refer to the insights provided by MSDN.

Keep these distinctions in mind as you work on your ASP/VBScript projects, and you’ll find it easier to handle numerical data effectively.