Strlen
strlen is a C library function that returns the number of characters in a null-terminated string before its terminating null character.
Modern C, Third Edition
strlen is a C standard-library function that returns the number of characters before the terminating zero in a string.
- How it is used
- Measures a zero-terminated string before copying, comparing, or sizing storage for it.
- How deep it goes
- Defines the first-zero rule, array-size distinction, termination requirement, and size_t result without detailing implementation internals.
- Examples
- Uses argv[0] to size a destination array before copying and comparing the program name.
- What you can do after
- Apply strlen through the C string library while preserving zero termination and allocating room for the terminator.
Modern C
strlen is a C standard library function that returns the number of characters before the null terminator of a string.
- How it is used
- Uses strlen to measure a null-terminated C string before allocating or copying storage.
- How deep it goes
- Defines the count and demonstrates allocation and copying, while deferring implementation internals.
- Examples
- Demonstrates measuring argv[0], sizing a variable-length array, copying characters, and adding the terminating 0.
- What you can do after
- Apply via the C standard library to measure valid strings and size storage for subsequent operations.
Related concepts
- stringuses · A string is a programming-language value representing an ordered sequence of characters or character units as text.
- memchralternative to · memchr is a C standard-library function that searches a specified memory region for the first byte having a given value.
- string.hconfigured by · string.h is the C standard library header declaring functions for manipulating strings, character arrays, and related memory sequences.
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