Split a string into token in C - c

Question

struct string {
size_t length;
size_t allocated;
char* data;
};
string* strCreate(char* str) {...}
string* strSubstring(string* str, size_t pos, size_t len) {...}
char* strGet(string* str) {
return str->data;
}
size_t findFrist(string* str, char what, size_t pos) {
for(size_t i = pos; i < str->length; ++i) {
if(str->data[i] == what)
return i;
}
return -1;
}
string** strTokenizer(string* str) {
string** res;
res = malloc(sizeof(char*)*90); //*90 (token num)
for(int i=0; i<90; i++) //i<90 (token num)
res[i] = malloc(sizeof(char)*100); //*100 (a token lenght)
size_t first = 0;
size_t i = 0;
while(first < str->length) {
int second = findFrist(str,' ',first);
if(second == - 1)
second = str->length;
string* token = strSubstring(str,first, second - first);
if(*strGet(token) != ' ')
res[i] = token;
first = second + 1;
++i;
}
return res;
}
int main() {
string* fe = strCreate("A string \ tof");
string** r = strTokenizer(fe);
for(int i = 0; i < 4; ++i) {
printf("%s",strGet(r[i]));
}
return 0;
}
I want to create a string tokenizer. When I want to print the string in the main function it not print the \. The other thing is that how to allocate string** res in proper way. When I allocate for the sizeof(char*) the only way that I see is loop through the string, but I was just wondering is this possible to allocate without going through the string 2 times in the tokenizer function.
I do not want to use strtok
typedef struct string string in the .h file

Answer 1

When compiling the code using GCC 10.2.0 with options:
gcc -O3 -g -std=c11 -Wall -Wextra -Werror …
I get the message:
bs83.c:85:44: error: unknown escape sequence: '\040' [-Werror]
85 | string *fe = strCreate("A string \ tof");
As I noted in the comments, the string "A string \ tof" is malformed — your compiler should be warning you about it. If you want a backslash in a string, you write (for example), "A string \\ tof". Backslash-space has no defined meaning; it is probably being interpreted as a single space. Maybe you should print the argument to strCreate() to validate this.
You also need typedef struct string string; near the top of the code for it to compile with a C compiler (and the headers).
Here is a fixed version of your code — because of the compilation options I use, the functions need to be either static or declared before being defined; I make them static since the only reason to make them non-static (IMO) is if they're accessed from another source file, and then they'd be declared in a header. That probably applies to your code — there is mention of a header.
Here's fixed code that works:
/* SO 6537-9584 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct string string;
struct string
{
size_t length;
size_t allocated;
char *data;
};
static
string *strCreate(char *str)
{
string *s = malloc(sizeof(string));
s->length = strlen(str);
s->allocated = s->length * 2;
s->data = (char *)malloc(s->allocated + 1);
memcpy(s->data, str, s->length);
s->data[s->length] = '\0';
return s;
}
static
string *strSubstring(string *str, size_t pos, size_t len)
{
string *s = malloc(sizeof(string));
s->length = len;
s->allocated = s->length * 2;
s->data = (char *)malloc(s->allocated + 1);
memcpy(s->data, &str->data[pos], s->length);
s->data[s->length] = '\0';
return s;
}
static
char *strGet(string *str)
{
return str->data;
}
static
size_t findFirst(string *str, char what, size_t pos)
{
for (size_t i = pos; i < str->length; ++i)
{
if (str->data[i] == what)
return i;
}
return -1;
}
static
string **strTokenizer(string *str)
{
string **res;
res = malloc(sizeof(char *) * 90); // *90 (token num)
for (int i = 0; i < 90; i++) // i<90 (token num)
res[i] = malloc(sizeof(char) * 100); // *100 (a token length)
size_t first = 0;
size_t i = 0;
while (first < str->length)
{
int second = findFirst(str, ' ', first);
if (second == -1)
second = str->length;
string *token = strSubstring(str, first, second - first);
if (*strGet(token) != ' ')
res[i] = token;
first = second + 1;
++i;
}
return res;
}
int main(void)
{
string *fe = strCreate("A string \\ tof");
string **r = strTokenizer(fe);
for (int i = 0; i < 4; ++i)
{
printf("[[%s]]\n", strGet(r[i]));
}
return 0;
}
The output is:
[[A]]
[[string]]
[[\]]
[[tof]]
Note the use of [[ and ]] around the printed strings (and the newlines). It makes it easier to identify trailing blanks and embedded carriage return characters and various other mishaps.