What\'s the Key Difference Between `%i` and `%d` in C\'s Formatted Input/Output?

Difference between Conversion Specifiers %i and %d in Formatted IO Functions

In formatted IO functions, such as printf and scanf, conversion specifiers are used to control the interpretation and formatting of input and output data. Among the various specifiers, %i and %d are frequently used for integers.

Output:

When used for output (e.g., with printf), %i and %d behave identically. They both represent an integer value and print it in the default format based on the system locale.

Input:

However, the distinction between %i and %d emerges during input operations (e.g., with scanf). Here, their behavior differs:

• %d: Scans an integer as a signed decimal number, represented in the basic arithmetic notation.
• %i: Primarily scans integers as signed decimal numbers, but it also allows hexadecimal and octal representations if they are prefixed appropriately. Hexadecimal numbers begin with "0x" (e.g., "0x20"), while octal numbers begin with "0" (e.g., "025").

Therefore, in the case of an input like "033", scanf("%d") interprets it as 33 (a signed decimal number), while scanf("%i") interprets it as 27 (an octal number), indicating a difference in representation.

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