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freadln.*: implement reading lines from arbitrary file

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Intel A80486DX2-66 2024-03-10 14:39:10 +03:00
parent 7d223427b6
commit e8d66db238
Signed by: 80486DX2-66
GPG Key ID: 83631EF27054609B
2 changed files with 34 additions and 7 deletions
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38
c-programming/io/freadln.c
View File

@ -10,13 +10,12 @@
* TODO: Figure out potential problems
* TODO: Add 'flushing' of STDIN (while there are characters, read them) before
* the input reading loop to avoid input queues
* TODO: Add the feature of reading from arbitrary file, then extract a macro:
* `#define finreadln(output, length_out) freadln(stdin, output, length_out)`
* FIXME: Handle EOF in a special way to indicate EOF
*/
#include "freadln.h"
int freadln(char** output, size_t* length_out) {
int freadln(FILE* f, char** output, size_t* length_out) {
/*
* The length of STDIN line is counted without any terminating characters.
*
@ -24,7 +23,7 @@ int freadln(char** output, size_t* length_out) {
* freadln_OK: no errors, the length of STDIN line has been stored in
* `length_out`
* freadln_ERROR: an error occurred (see errno)
* >= 0: length of stdin line
* >= 0: length of read line
*/
if (output == NULL)
@ -41,7 +40,7 @@ int freadln(char** output, size_t* length_out) {
return freadln_ERROR;
int character;
while ((character = fgetc(stdin)) != EOF
while ((character = fgetc(f)) != EOF
/* stop on a newline character: */ && character != '\n') {
(*output)[length] = (char) character;
@ -71,13 +70,40 @@ int freadln(char** output, size_t* length_out) {
#ifdef TEST
int main(void) {
// stdin test
printf("Type something> ");
char* line;
if (freadln(&line, NULL) != freadln_OK) {
if (finreadln(&line, NULL) != freadln_OK) {
perror("freadln");
exit(EXIT_FAILURE);
}
printf("Input string: '%s'\n", line);
// file test
#define TEST_FILE "freadln_test.txt"
FILE* f = fopen(TEST_FILE, "w");
if (f == NULL) {
perror("fopen");
exit(EXIT_FAILURE);
}
fprintf(f, "Hello, world!\nAnother line\n\n");
FILE* new_f = freopen(TEST_FILE, "r", f);
if (new_f == NULL) {
perror("freopen");
exit(EXIT_FAILURE);
}
f = new_f;
for (int i = 0; i < 5; i++) {
size_t line_length;
if (freadln(f, &line, &line_length) != freadln_OK) {
perror("freadln");
exit(EXIT_FAILURE);
}
printf("File, line #%d: '%s' (%zu characters)\n", i + 1, line,
line_length);
}
fclose(f);
return 0;
}
#endif

3
c-programming/io/freadln.h
View File

@ -26,6 +26,7 @@ enum freadln_status {
return freadln_OK; \
} while (0)
int freadln(char** output, size_t* length_out);
int freadln(FILE* f, char** output, size_t* length_out);
#define finreadln(output, length_out) freadln(stdin, output, length_out)
#endif /* _FREADLN_H */