Header Files

#include <string.h>

Creating Strings

	static const char *my_define = "/etc/sysconfig/network";

	const char *mytext = "Hello World";

String Length

	int mytext_length = strlen(mytext);

Does String Contain

	if (strncmp(*++argv, "O_RDONLY", 8) == 0)
		open_mode |= O_RDONLY;

Copy String

The preferred way

	strncpy (string_destination, string_source, max_length);		//Note no null will be included if the string is >= max_length

The more dangerous way

	strcpy (string_destination, string_source);

Return A Char Array From A Function

You need to dynamically allocate your char array.

For C++:

char *recvmsg(){
   char* buffer = new char[1024];
   return buffer;
}

For C:

char *recvmsg(){
   char* buffer = malloc(1024);
   return buffer;
}

Without this dynamic allocation the variable will reside on the function's stack and will therefore be destroyed on exit. This is why you will typically get a warning if you do this. Allocating it on the heap prevents this, BUT you will have to be careful and free the memory once done with it via delete[].

Replace String With String

//************************************************
//************************************************
//********** REPLACE STRING WITH STRING **********
//************************************************
//************************************************
//Look for first occurrence of a string and replace it with a new string
//The new outputted string is stored in original_string
int string_replace_string_with_string (char *original_string, char *find_string, char *replace_with_string)
{
	char buffer[MAX_STRING_LENGTH];
	char *p;

	p = strstr(original_string, find_string);						//Find first occurrence of the string
	if (p)
	{
		strncpy(buffer, original_string, p - original_string);		//Copy characters from original_string start to find_string st$
		buffer[p - original_string] = '';
		snprintf(buffer + (p - original_string),
				(MAX_STRING_LENGTH - (int)(buffer + (p - original_string))),
				"%s%s",
				replace_with_string,
				p + strlen(find_string));

		strncpy(original_string, buffer, MAX_STRING_LENGTH);		//Copy back into the original string
		return(1);
	}
	return(0);
}
/* Using the function:
#define	MAX_STRING_LENGTH 	1024

char original_string[MAX_STRING_LENGTH] = {"There are many variations of passages of Lorem Ipsum available, but are the majority have suffered alteration in some form"};
char find_string[] = {"are"};
char replace_with_string[] = {"z"};

string_replace_string_with_string (original_string, find_string, replace_with_string, MAX_STRING_LENGTH);
printf("nnMODIFIED STRING:n%sn", original_string);
*/

Find String Between Strings

//*************************************************
//*************************************************
//********** FIND STRING BETWEEN STRINGS **********
//*************************************************
//*************************************************
//Looks for first occurrence of a string1 and string2 and outputs the string between them
int string_find_string_between_strings (char *source_string, char *find_string1, char *find_string2, char *result_string)
{
	char *p_1;
	char *p_2;

	//Default to a null output string
	*result_string = '';

	p_1 = strstr(source_string, find_string1);
	p_2 = strstr(source_string, find_string2);

	if (p_1 && p_2)
	{
		//Exclude the search strings from the result
		p_1 += strlen(find_string1);

		//Ensure they are the right way round
		if (p_2 < p_1)
			return(0);

		int length = (p_2 - p_1);
		if (length > (MAX_STRING_LENGTH - 1))
			length = (MAX_STRING_LENGTH - 1);

		//Ensure the final byte is null
		result_string[length]  = '';


		strncpy(result_string, p_1, length);		//Copy characters from original_string start to find_string st$

		return(1);
	}
	return(0);
}
/* Using the function:
	#define	MAX_STRING_LENGTH 	1024

	char original_string[] = {"There are many variations of passages of Lorem Ipsum available, but the majority have suffered alteration in some form"};
	char find_string1[] = {"are "};
	char find_string2[] = {" but"};
	char result_string[MAX_STRING_LENGTH];

	string_find_string_between_strings(original_string, find_string1, find_string2, result_string, MAX_STRING_LENGTH);
	printf("nFOUND STRING:n[%s]n", result_string);
 */

 

Get String Up To String

//*********************************************
//*********************************************
//********** GET STRING UP TO STRING **********
//*********************************************
//*********************************************
//Looks for first occurrence of a string and outputs the string up to that string
int string_get_string_up_to_string (char *source_string, char *find_string, char *result_string)
{
	char *p;

	//Default to a null output string
	*result_string = '';

	p = strstr(source_string, find_string);
	if (p)
	{
		int length = (p - source_string);
		if (length > (MAX_STRING_LENGTH - 1))
			length = (MAX_STRING_LENGTH - 1);

		//Ensure the final byte is null (won't be added by strncpy if resutlt > MAX_STRING_LENGTH)
		result_string[length]  = '';


		strncpy(result_string, source_string, length);		//Copy characters from original_string start to find_string st$

		return(1);
	}
	return(0);
}
/* Using the function:
#define	MAX_STRING_LENGTH 	1024

char source_string[] = {"There are many variations of passages of Lorem Ipsum available, but the majority have suffered alteration in some form"};
char find_string[] = {" but "};
char result_string[MAX_STRING_LENGTH];

	string_get_string_up_to_string (source_string, find_string, result_string);
	printf("nBefore string:n[%s]n", result_string);
*/

Get String After String

//*********************************************
//*********************************************
//********** GET STRING AFTER STRING **********
//*********************************************
//*********************************************
//Looks for first occurrence of a string and outputs the string after that string
int string_get_string_after_string (char *source_string, char *find_string, char *result_string)
{
	char *p;

	//Default to a null output string
	*result_string = '';

	p = strstr(source_string, find_string);
	if (p)
	{
		p += strlen(find_string);

		//Ensure the final byte is null (won't be added by strncpy if resutlt > MAX_STRING_LENGTH)
		result_string[(MAX_STRING_LENGTH - 1)]  = '';

		strncpy(result_string, p, (MAX_STRING_LENGTH - 1));		//Copy characters from original_string start to find_string st$

		return(1);
	}
	return(0);
}
/* Using the function:
#define	MAX_STRING_LENGTH 	1024

char source_string[] = {"There are many variations of passages of Lorem Ipsum available, but the majority have suffered alteration in some form"};
char find_string[] = {" but "};
char result_string[MAX_STRING_LENGTH];

	string_get_string_after_string (source_string, find_string, result_string);
	printf("nAfter string:n[%s]n", result_string);
*/