C Language: Strings and Characters

This repository is dedicated to practicing and studying character and string manipulation in the C programming language, covering everything from basic fundamentals to advanced library usage.

Summary of Topics

1. Character Manipulation (ctype.h)

Study of functions for verifying and converting individual characters:

• Verification: isdigit(), isalpha(), isalnum(), islower(), isupper(), ispunct(), and isspace().
• Conversion: tolower() and toupper().

2. String Fundamentals

• Definition: Strings in C are sequences of characters terminated by the null character \0.
• Safe Input/Output: Using fgets() for safe reading (avoiding buffer overflow) and puts() or printf() for display.
• Character Access: Iterating through strings using the idiomatic for (int i = 0; str[i] != '\0'; i++) pattern.

3. Standard Libraries

string.h - Essential Functions

• strlen(): Returns the string length.
• strcpy() / strncpy(): Copying strings.
• strcat() / strncat(): Concatenation.
• strcmp() / strncmp() / stricmp(): String comparison.
• Advanced Search & Utility: strchr(), strrchr(), strstr(), strrev(), and strset().

stdlib.h - Type Conversion

• atoi(): String to int.
• atof(): String to float/double.
• itoa(): Integer to string.

Best Practices Applied

• Memory Safety: Always reserving space for the null terminator (N+1).
• Secure I/O: Preferring fgets() over gets() (which is deprecated and unsafe).
• Performance: Calculating strlen() once before long loops to avoid redundant processing.