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C String Library

The C standard library provides a comprehensive set of functions to manipulate strings in the <string.h> header file. Here are some of the most commonly used functions:

strcpy: Copies a string to another.

char src[] = "Hello";
char dest[6];
strcpy(dest, src);
// dest now contains "Hello"

strncpy: Copies a specified number of characters from one string to another.

char src[] = "Hello";
char dest[6];
strncpy(dest, src, 3);
// dest now contains "Hel"
dest[3] = '\0';
// ensure null termination

strcat: Concatenates (appends) one string to another.

char dest[12] = "Hello";
char src[] = " World";
strcat(dest, src);
// dest now contains "Hello World"

strncat: Concatenates a specified number of characters from one string to another.

char dest[12] = "Hello";
char src[] = " World";
strncat(dest, src, 3);
// dest now contains "Hello Wo"

strlen: Returns the length of a string (excluding the null terminator).
```
char str[] = "Hello";
size_t len = strlen(str);
// len is 5
```

strcmp: Compares two strings lexicographically.

char str1[] = "Hello";
char str2[] = "World";
int result = strcmp(str1, str2);
// result is negative since "Hello" < "World"

strchr: Finds the first occurrence of a character in a string.

char str[] = "Hello";
char *pos = strchr(str, 'l');
// pos points to the first 'l' in "Hello"

strstr: Finds the first occurrence of a substring in a string.

char str[] = "Hello World";
char *pos = strstr(str, "World");
// pos points to "World" in "Hello World"

Assignment

Complete the smart_append function. It appends a src string to the buffer field inside the dest TextBuffer struct.

The TextBuffer struct tracks both the buffer and its current length. It's called a "smart" append because the destination buffer is a fixed 64 bytes, and it:

Checks for available space before appending.
Appends as much as possible if there's not enough space.
Always ensures the buffer remains null-terminated.
Returns a status indicating whether the full append was possible.

Here are the steps:

If either the dest or src input is NULL, return 1 (failure). The input pointer checks can be done with ptr == NULL or !ptr.

In C, NULL represents a null pointer, which does not point to a value.
Create a constant to represent the max buffer size of 64.
Get the length of the src string using strlen.
Calculate the remaining space in the dest buffer. Notice that it stores its own length. The 64-byte buffer can hold 63 characters plus the null terminator.
If the src string is larger than the remaining space:
1. Copy as much of the src string as possible to the dest buffer using strncat.
2. Update the dest buffer length to the max size, accounting for the null terminator.
3. Return 1 (failure) to indicate the full append wasn't possible.
Otherwise, if there's enough space:
1. Append the entire src string to the dest buffer using strcat.
2. Update the dest buffer length.
3. Return 0 (success) to indicate the full append was possible.