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#include <stdio.h>
#include <string.h>
#include <zsv.h>
/**
* Simple example using libzsv to call a row handler after each row is parsed
*
* In this super simple example, we will use libzsv to parse a CSV file
* and call our custom row handler after each row is parsed. Our row handler
* will check each cell in the row to determine if it is blank, and output
* the row number, the total number of cells and the number of blank cells
*
* Example:
* `echo 'abc,def\nghi,,,' | build/simple -`
* Outputs:
* Row 1 has 2 columns of which 0 are non-blank
* Row 2 has 4 columns of which 3 are non-blank
*/
/**
* First, we define a structure that will contain all the information that
* our row handler will need
*/
struct my_data {
zsv_parser parser; /* used to access the parsed data */
size_t row_num; /* used to track the current row number */
};
/**
* Our row handler is passed a pointer to our structure
*/
void my_row_handler(void *ctx) {
struct my_data *data = ctx;
/* get a cell count */
size_t cell_count = zsv_cell_count(data->parser);
/* iterate through each cell in this row, to count blanks */
size_t nonblank = 0;
for (size_t i = 0; i < cell_count; i++) {
/* use zsv_get_cell() to get our cell data */
struct zsv_cell c = zsv_get_cell(data->parser, i);
/* check if the cell data length is zero */
if (c.len > 0)
nonblank++;
}
/* print our results for this row */
printf("Row %zu has %zu columns of which %zu %s non-blank\n", ++data->row_num, cell_count, nonblank,
nonblank == 1 ? "is" : "are");
}
/**
* Main routine. Our program will take a single argument (a file name, or -)
* and output, for each row, the numbers of total and blank cells
*/
int main(int argc, const char *argv[]) {
/**
* Process our arguments; output usage and/or errors if appropriate
*/
if (argc != 2) {
fprintf(stderr, "Reads a CSV file or stdin, and for each row,\n"
" output counts of total and blank cells\n");
fprintf(stderr, "Usage: simple <filename or dash(-) for stdin>\n");
fprintf(stderr,
"Example:\n"
" echo \"A1,B1,C1\\nA2,B2,\\nA3,,C3\\n,,C3\" | %s -\n\n",
argv[0]);
return 0;
}
FILE *f = strcmp(argv[1], "-") ? fopen(argv[1], "rb") : stdin;
if (!f) {
perror(argv[1]);
return 1;
}
/**
* Configure our parser options. Here, all we do is specify our row handler
* and the pointer that will be passed to our row handler. There are many
* other options to control the parser behavior (CSV vs TSV vs other
* delimited; header row span etc)-- for details, see
* ../../include/zsv/api.h
*/
struct zsv_opts opts = {0};
opts.row_handler = my_row_handler;
struct my_data data = {0};
opts.ctx = &data;
opts.stream = f;
/**
* Create a parser
*/
data.parser = zsv_new(&opts);
/**
* Continuously parse our input until we have no more input
*/
enum zsv_status stat;
while ((stat = zsv_parse_more(data.parser)) == zsv_status_ok)
;
/**
* Clean up
*/
zsv_finish(data.parser);
zsv_delete(data.parser);
if (f != stdin)
fclose(f);
/**
* If there was a parse error, print it
*/
if (stat != zsv_status_no_more_input) {
fprintf(stderr, "Parse error: %s\n", zsv_parse_status_desc(stat));
return 1;
}
return 0;
}
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