Difference between Character Array and String in C

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Question: What is Difference Between Character Array and String Literal in C Language?

Answer: Let’s, first, consider following declarations,

    #define STR_LIT "I'm string literal declared using #define"
    char *str_lit = "I'm string literal declared through pointer-to-char";
    char char_arr[5] = {'a','b','c','d','e'};    /* character array */

Let’s, now, embed them into a program below,

/* 
 * diff_chararr_strlit.c -- program differentiates char array and string
 * literal
 */
#include <stdio.h>
#define STR_LIT "I'm string literal declared using #define"
 
int main(void)
{
    char *str_lit = "I'm string literal declared through pointer-to-char";
    char char_arr[5] = {'a','b','c','d','e'};    /* character array */
 
    puts("\n*****Program differentiates character array and "
         "string literal*****\n");
    puts(STR_LIT);         /* add. of string literal passed to puts */
    puts(str_lit);
    puts("\n");
    puts("Let's, now, try to access character array as character string..."
         "\n");
    puts(char_arr);
    puts("\n");
    return 0;
}

Output of above program when run on Linux Machine is as below,

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*****Program differentiates character array and string literal*****
 
I'm string literal declared using #define
I'm string literal declared through pointer-to-char
 
Let's, now, try to access character array as character string...
 
abcde

So, what here you observed when accessed character array ‘char_arr as character string by passing its address to puts? Output contains all characters from the ‘char_arr’ with some extra unspecified characters appended in the end. How’s this? Actually, puts prints characters until it finds NULL terminator. Since, ‘char_arr’ wasn’t containing one therefore puts continued after the end of ‘char_arr’ until it found one. Then how to access character arrays? It’s easy, use loops with counter explicitly specifying no. of characters in character array. For example, to access ‘char_arr’,

    for (i = 0; i < 5; i++)
        putc(char_arr[i]);    /* or printf("%c", char_arr[i]) */

String literals whether declared using #define statements or using pointer-to-char contain NULL bytes. In initialization

    char *str_lit = "I'm string literal declared through pointer-to-char";

‘str_lit’ is a pointer to string “I’m string literal declared through pointer-to-char” wherever stored in memory. In string literals or string constants, there’s no visible NULL terminator. Compiler appends it with NULL terminator while compiling the program.

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There’s one more basic difference between character array and string literal and that is string literals, like symbolic constants, are constant strings while character arrays aren’t.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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