csv

commit d666838b2ad0776a1e2bb9fef8e2e8ef6de60278
parent 1f76650300e3a22379f84779f0763967907ebc53
Author: phoebos <ben@bvnf.space>
Date:   Sat,  2 Oct 2021 12:47:56 +0000

add flag to optionally scan for header line

Diffstat:
M
Makefile
 | 
2
+-
M
csv.c
 | 
58
+++++++++++++++++++++++++++++++++++++++++-----------------

2 files changed, 42 insertions(+), 18 deletions(-)
diff --git a/Makefile b/Makefile
@@ -1,5 +1,5 @@
 .POSIX:
-XCFLAGS = $(CFLAGS) -Wall -Wextra -Wpedantic -Og -ggdb3
+XCFLAGS = $(CFLAGS) -Wall -Wextra -Wpedantic -Og -ggdb3 -D_XOPEN_SOURCE=600
 
 csv: csv.c
 	$(CC) $(XCFLAGS) -o $@ $<
diff --git a/csv.c b/csv.c
@@ -36,33 +36,57 @@ read_header(FILE *f, char ***header) {
 
 int
 main(int argc, char **argv) {
-	if (argc > 2) {
-		fprintf(stderr, "usage: %s [file]\n\tif no filename given, data is \
-read from stdin\n", argv[0]);
+	int c;
+	int flag_H = 0;
+	while ((c = getopt(argc, argv, "H")) != -1) {
+		switch (c) {
+			case 'H':
+				flag_H = 1;
+				break;
+		}
+	}
+	if (argc - optind > 1) {
+		fprintf(stderr,
+			"usage: %s [-H] [file]\n  if no filename given, data is \
+read from stdin\n"
+			"  -H\tread data headers from first line\n", argv[0]);
 		return 1;
 	}
 	FILE *f;
-	if (argc == 1) {
+	if (argc - optind == 0) {
 		f = stdin;
 	} else {
-		f = fopen(argv[1], "r");
+		f = fopen(argv[optind], "r");
 		if (f == NULL) {
-			perror(argv[1]);
+			perror(argv[optind]);
 			return 1;
 		}
 	}
 
-	int ncols;
+	int ncols = 0;
 
-	/* read header */
-	char **header = malloc(sizeof (char *) * MAX_LINE);
-	ncols = read_header(f, &header);
-	for (int i = 0; i < ncols; i++) {
-		printf("%s\t", header[i]);
-		free(header[i]);
+	if (flag_H) {
+		/* read header */
+		char **header = malloc(sizeof (char *) * MAX_LINE);
+		ncols = read_header(f, &header);
+		for (int i = 0; i < ncols; i++) {
+			printf("%s\t", header[i]);
+			free(header[i]);
+		}
+		printf("\n");
+		free(header);
+	} else {
+		/* scan the first line to get the value of ncols */
+		while ((c = fgetc(f)) != EOF) {
+			if (c == ',') ncols++;
+			if (c == '\n') {
+				ncols++;
+				break;
+			}
+		}
+		/* ensure we can properly scan the first line when we come to it */
+		rewind(f);
 	}
-	printf("\n");
-	free(header);
 
 	/* read data */
 	char *n = malloc(MAX_LINE);
@@ -80,7 +104,7 @@ read from stdin\n", argv[0]);
 		goto fail;
 	}
 	np = n;
-	int c, x, y;
+	int x, y;
 	x = y = 0;
 	while ((c = fgetc(f)) != EOF) {
 		if (c == ',' || c == '\n') {
@@ -119,7 +143,7 @@ read from stdin\n", argv[0]);
 			printf("%g\t", data[i][j]);
 		printf("\n");
 	}
-	printf("table has %d rows of %d columns\n", nrows, ncols);
+	fprintf(stderr, "table has %d rows of %d columns\n", nrows, ncols);
 
 	free(n);
 	free(data);