What\'s the Key Difference Between `%i` and `%d` Format Specifiers in C\'s `printf` and `scanf`?

Understanding the Difference Between Format Specifiers %i and %d

When utilizing formatted input/output functions like printf and scanf, the format specifiers play a crucial role in controlling the type of data to be printed or read. Among these, the specifiers %d (integer) and %i (integer) warrant careful consideration.

Usage in printf

For output operations, there is no functional difference between %d and %i. Both will output a signed decimal integer. For instance, using either %d or %i with the integer value 100 would result in the string "100".

Usage in scanf

However, the distinction between %d and %i becomes evident in input operations. While %d strictly scans a signed decimal integer, %i supports decimal, hexadecimal, and octal formats.

• Decimal (default): Both %d and %i will accept a sequence of decimal digits (e.g., 123, -45).
• Hexadecimal: %i allows input in hexadecimal format if prefixed with "0x" (e.g., 0x123). On the other hand, %d will treat "0x" as part of the integer string.
• Octal: Similarly, %i supports octal input if prefixed with "0" (e.g., 033). In contrast, %d would interpret "033" as a decimal integer.

To illustrate the difference, consider the following example:

scanf("%i", &number);

If the user enters "033", %i will interpret it as an octal number and assign the value 27 to the variable 'number', whereas %d would assign 33.

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