csv_reader.c
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#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <stdlib.h>
// Conditionals
const bool IS_DEBUG = false;
// Constants
const unsigned int BUFFER_SIZE = 2048;
const unsigned int FIELD_SIZE = 20;
const char CSV_DELIMITERS[] = ",";
// Globals
char** CSV_HEADER_FIELDS;
unsigned int CSV_NB_FIELDS;
void display_header()
{
for(unsigned int i = 0; i < CSV_NB_FIELDS; i++)
{
printf("%d - %s\n", i, CSV_HEADER_FIELDS[i]);
}
}
void read_csv_header(char * header_line)
{
int line_length = strlen(header_line);
int nb_fields = 0;
char* string_ptr = header_line;
// Count the occurrences of delimiters
while (NULL != string_ptr)
{
nb_fields++;
string_ptr = strpbrk(string_ptr, CSV_DELIMITERS);
if (NULL != string_ptr)
{
string_ptr++;
}
}
// Globals allocation
CSV_NB_FIELDS = nb_fields;
CSV_HEADER_FIELDS = malloc( nb_fields * sizeof(char*) );
char* token = strtok(header_line, CSV_DELIMITERS); // strtok init.
// Re-read the line to get the header of the columns
for (unsigned int i = 0; i < nb_fields; i++)
{
CSV_HEADER_FIELDS[i] = malloc( FIELD_SIZE * sizeof(char) ); // alloc
memset(CSV_HEADER_FIELDS[i], 0, FIELD_SIZE); // 0 init.
strcpy(CSV_HEADER_FIELDS[i], token); // copy field in the structure
token = strtok(NULL, CSV_DELIMITERS); // loop to get a new field label
}
if (IS_DEBUG) display_header();
}
void read_csv_file(const char * filename)
{
FILE* fp = fopen(filename, "r");
char buffer[BUFFER_SIZE];
// Check if the file is really opened
if (NULL == fp)
{
fprintf(stderr, "Unable to open file: %s\n", filename);
return;
}
// 1st row is a header with field descriptions
fgets(buffer, BUFFER_SIZE, fp);
read_csv_header(buffer);
// Remaining rows are the entries
while ( NULL != fgets(buffer, BUFFER_SIZE, fp) )
{
char* token;
unsigned int i = 0;
// strtok init.
token = strtok(buffer, CSV_DELIMITERS);
while (NULL != token)
{
if (IS_DEBUG) printf("Field %d is %s\n", i++, token);
// ...
// you can strcpy the `token` string in your data structures
// ...
token = strtok(NULL, CSV_DELIMITERS);
}
}
fclose(fp);
}
void usage(const char * prog_name)
{
printf("Usage is %s your_csv_file\n\n", prog_name);
}
int main(int argc, char * argv[])
{
if (2 != argc)
{
usage(argv[0]);
return 0;
}
read_csv_file(argv[1]);
for(unsigned int i = 0; i < CSV_NB_FIELDS; i++)
{
free(CSV_HEADER_FIELDS[i]);
}
free(CSV_HEADER_FIELDS);
return 0;
}