How Can I Customize String Truncation in printf()?

Customizing String Truncation in printf()

Query:

Is it possible to control the number of characters printed from a string using printf(), akin to specifying decimal places for integers?

Consider:

printf("Here are the first 8 chars: %sn", "A string that is more than 8 chars");

Expected output: Here are the first 8 chars: A string

Solution:

There are two primary methods for achieving this customization:

Method 1:

printf("Here are the first 8 chars: %.8sn", "A string that is more than 8 chars");

Method 2:

printf("Here are the first %d chars: %.*sn", 8, 8, "A string that is more than 8 chars");

In the second method, an integer argument is passed to printf(), specifying the length. The '*' in the format prompts printf() to obtain the length from the accompanying argument.

An alternative notation exists:

printf("Here are the first 8 chars: %*.*sn", 8, 8, "A string that is more than 8 chars");

This notation is akin to the "%8.8s" format but allows for dynamic specification of minimum and maximum lengths, especially useful in scenarios like:

printf("Data: %*.*s Other info: %dn", minlen, maxlen, string, info);

The POSIX specification for printf() provides a detailed explanation of these mechanisms.

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