I wrote c code which input value for my program comes from here :
char *input[] = {"This input string value !!!", NULL};
But how can I read this value from the file (e.g. input.txt)? Is it possible to get the file content like a string?
Thanks a lot!
If you want to read a file line-by-line, the easiest way to go is using getline. Read the man page for a detailed description and a good code example.
getline will do all the low-lvel plumbing work of allocating buffers, copying data and scanning for newline characters, etc for you. Keep in mind that this is only possible since getline uses dynamically allocated memory that you'll need to free again.
You can use fgets() like this:
#include <stdio.h>
int main(void)
{
char buffer[100];
FILE *file = fopen("input.txt", "r");
// Checks if the file was opened successfully
if (file == NULL)
{
fputs("Failed to open the file\n", stderr);
return -1;
}
// fgets here reads an entire line or 99 characters (+1 for \0) at a time, whichever comes first
while (fgets(buffer, sizeof(buffer), file) != NULL)
{
printf("Line read = %s\n", buffer);
}
fclose(file);
}
You can also use fgetc() like this:
#include <stdio.h>
int main(void)
{
int ch;
FILE *file = fopen("input.txt", "r");
// Checks if the file was opened successfully
if (file == NULL)
{
fputs("Failed to open the file\n", stderr);
return -1;
}
// fgetc reads each character one by one until the end of the file
while ((ch = fgetc(file)) != EOF)
{
printf("Character read = %c\n", ch);
}
fclose(file);
}
fgetc then...I'll update my answermalloc() like this : char *ch;ch=(char*)malloc(100*sizeof(char));On recent Posix compliant systems you could use getline(3), something like
FILE *fil = fopen("somefile.txt", "r");
if (!fil) {perror("somefile.txt"); exit(EXIT_FAILURE); };
char*linbuf = NULL;
size_t siz = 0;
ssize_t linlen = 0;
while ((linlen=getline(&linbuf, &siz, fil))>0) {
// linbuf contains the current line
// linlen is the length of the current line
do_something_with(linbuf, linlen);
};
fclose(fil);
free(linbuf), linbuf=NULL;
linlen = 0, siz = 0;
