Split char array in C while keeping delimiters - c

Question

So I'm working in C and have a char array and I want to split it everytime there is a space, "(", ")", or "{". But, I want to keep those character delimiters. For example, if my input was
void statement(int y){
I want my output to be
void
statement
(
int
y
)
{
What's the best way to go about this?

Answer 1

You can do it with the loop of your choice and a few conditional tests that basically boil down to:
if the current char is a delimiter;
if the previous char wasn't a delimiter, output a space before the delimiter;
if the delimiter (current char) is not a space, output char followed by newline.
(using the string of delimiters as the string in strchr and checking against the current char is a simple way of determining if the current char is a delim)
Putting that together in a short example, you could do something similar to:
#include <stdio.h>
#include <string.h>
int main (void) {
int c, last = 0; /* current & previous char */
const char *delims = " (){}"; /* delimiters */
while ((c = getchar()) != EOF) { /* read each char */
if (strchr (delims, c)) { /* if delimiter */
if (last && !strchr (delims, last)) /* if last not delimiter */
putchar ('\n'); /* precede char with newline */
if (c != ' ') { /* if current not space */
putchar (c); /* output delimiter */
putchar ('\n'); /* followed by newline */
}
}
else /* otherwise */
putchar (c); /* just output char */
last = c; /* set last to current */
}
}
Example Use/Output
Given your input string, the output matches what you have provided.
$ printf "void statement(int y){" | ./bin/getchar_delims
void
statement
(
int
y
)
{
Look things over and let me know if you have further questions.

Answer 2

You can try using strpbrk, which not only retains the delimiting chars by simply returning a pointer to the found delimiter, but also supports multiple delimiter characters.
For example, this should do what you want:
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
int main(int argc, char *argv[]) {
char *input = "void statement(int y){a";
char *delims = " (){";
char *remaining = input;
char *token;
// while we find delimiting characters
while ((token = strpbrk(remaining, delims)) != NULL) {
// print the characters between the last found delimiter (or string beginning) and current delimiter
if (token - remaining > 0) {
printf("%.*s\n", token - remaining, remaining);
}
// Also print the delimiting character itself
printf("%c\n", *token);
// Offset remaining search string to character after the found delimiter
remaining = token + 1;
}
// Print any characters after the last delimiter
printf("%s\n", remaining);
return 0;
}
The output includes the spaces since you included as a delimiter. If you don't want this, wrap the delimiter character printing in a condition like this:
if (*token != ' ') {
printf("%c\n", *token);
}