A C string is a 0-terminated array of char. The terminating zero is an additional element: "hello" occupies six char elements, although only five characters are visible. section 6.1.5
char jay0[] = "jay";
char jay1[] = { "jay" };
char jay2[] = { 'j', 'a', 'y', 0, };
char jay3[4] = { 'j', 'a', 'y', };
These declarations initialize equivalent four-element arrays containing j, a, y, and the terminating zero. section 6.1.5
Capacity determines whether an array is a string
char jay4[3] = { 'j', 'a', 'y', }; char jay5[3] = "jay"; Both arrays contain the visible characters but have no remaining element for the terminating zero, so neither is a C string. Arrays also cannot be assigned after initialization. section 6.1.5
The type char encodes characters from C’s basic character set. Standard-library facilities in <string.h> distinguish byte-oriented mem functions, which receive an explicit length, from str functions, which require 0-terminated strings. section 6.1.5
Listing 6.2 Using some of the string functions
#include <string.h>
#include <stdio.h>
int main(int argc, char* argv[argc+1]) {
size_t const len = strlen(argv[0]); // Computes the length
// Initialized VLA, C23
// terminates array with 0 character
char name[len+1] = { };
// Copies the program name
memcpy(name, argv[0], len);
if (!strcmp(name, argv[0])) {
printf("program name "%s" successfully copied\n",
name);
} else {
printf("copying %s leads to different string %s\n",
argv[0], name);
}
}
This program computes a string length, allocates space for its terminator, copies the characters with memcpy, and compares the result with strcmp. section 6.1.5
