Join array of strings into a single string
/*
Beginning C, Third Edition
By Ivor Horton
ISBN: 1-59059-253-0
Published: Apr 2004
Publisher: apress
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define MAX_STRINGS 100 /* Maximum string count */
#define BUFFER_SIZE 50 /* Initial input buffer size */
char* join_strings(char *strings[], int count); /* Joins array of strings into a single string */
char* read_string(); /* Reads a string from the keyboard */
void main()
{
char *pStrings[MAX_STRINGS]; /* Array of pointers to strings */
char *joined_strings = NULL; /* Pointer to the joined string */
int count = 0; /* Number of strings entered */
char answer = 'y'; /* Confirms more input */
char terminator = '*'; /* Terminator for string entry */
int i = 0;
/* Read the strings */
while(count<MAX_STRINGS && tolower(answer)=='y')
{
printf("Enter a string:\n");
pStrings[count++] = read_string(terminator);
printf("Do you want to enter another: ");
scanf(" %c", &answer);
fflush(stdin); /* Lose newline following character entry */
}
joined_strings = join_strings(pStrings, count);
printf("\nHere are the strings as a single string:\n%s\n", joined_strings);
free(joined_strings); /* Free memory for joined strings */
for(i = 0 ; i<count ; i++) /* Free memory for original strings */
free(pStrings[i]);
}
/************
* Function to join an array of strings *
* this function allocates memory that must be freed by the caller *
************/
char* join_strings(char *strings[], int count)
{
char* str = NULL; /* Pointer to the joined strings */
size_t total_length = 0; /* Total length of joined strings */
size_t length = 0; /* Length of a string */
int i = 0; /* Loop counter */
/* Find total length of joined strings */
for(i = 0 ; i<count ; i++)
{
total_length += strlen(strings[i]);
if(strings[i][strlen(strings[i])-1] != '\n')
++total_length; /* For newline to be added */
}
++total_length; /* For joined string terminator */
str = (char*)malloc(total_length); /* Allocate memory for joined strings */
str[0] = '\0'; /* Empty string we can append to */
/* Append all the strings */
for(i = 0 ; i<count ; i++)
{
strcat(str, strings[i]);
length = strlen(str);
/* Check if we need to insert newline */
if(str[length-1] != '\n')
{
str[length] = '\n'; /* Append a newline */
str[length+1] = '\0'; /* followed by terminator */
}
}
return str;
}
/********************
* Reads a string of any length. *
* The string is terminated by the chracter passed as the argument. *
* Memory is allocated to hold the string and must be freed by the caller. *
********************/
char* read_string(char terminator)
{
char *buffer = NULL; /* Pointer to the input buffer */
int buffersize = BUFFER_SIZE; /* Current buffer capacity */
int length = 0; /* String length */
char *temp = NULL; /* Temporary buffer pointer */
int i = 0; /* Loop counter */
buffer = (char*)malloc(BUFFER_SIZE); /* Initial buffer */
/* Read the string character by character */
for(;;)
{
/* Check for string terminator */
if((buffer[length] = getchar()) == terminator)
break;
else
++length;
/* Check for buffer overflow */
if(length == buffersize)
{
buffersize += BUFFER_SIZE; /* Increase buffer size */
temp = (char*)malloc(buffersize); /* Allocate new buffer */
/* Copy characters from old buffer to new */
for(i = 0 ; i<length ; i++)
temp[i] = buffer[i];
free(buffer); /* Free memory for old buffer */
buffer = temp; /* Store new buffer address */
temp = NULL; /* Rest temp pointer */
}
}
buffer[length] = '\0'; /* Append string terminator */
temp = (char*)malloc(length+1); /* Allocate exact memory required for string */
strcpy(temp, buffer); /* Copy the string */
free(buffer); /* Free the buffer memory */
return temp;
}