Split a String Using Delimiter

Question

Problem: Split a String Using Delimiter. Solve this hands-on electronics task on EWskills.

Accepted Answer

#include 
#include 

void split_string(const char *str, char delimiter, char tokens[10][20], uint8_t *count) {
    uint8_t row = 0, col = 0;
    *count = 0;

    for (uint8_t i = 0; str[i] != '\0'; i++) {
        if (str[i] == delimiter) {
            if (col > 0) {
                tokens[row][col] = '\0';  // End current token
                row++;
                col = 0;
            }
        } else {
            if (col < 19) {
                tokens[row][col++] = str[i];
            }
        }
    }

    // Final token
    if (col > 0) {
        tokens[row][col] = '\0';
        row++;
    }

    *count = row;
}

int main() {
   char str[101];
   char delimiter;
   fgets(str, sizeof(str), stdin);
   scanf(" %c", &delimiter);

   // Remove newline
   uint8_t i = 0;
   while (str[i]) {
       if (str[i] == '
') { str[i] = '\0'; break; }
       i++;
   }

   char tokens[10][20];
   uint8_t count = 0;

   split_string(str, delimiter, tokens, &count);

   for (uint8_t i = 0; i < count; i++) {
       printf("%s
", tokens[i]);
   }

   return 0;
}

What is this about?

Simulate splitting a string on a delimiter without using strtok(), and store tokens manually in a 2D char array.

Why it matters in firmware?

strtok() uses static memory and is not reentrant — not ideal in interrupt routines or multi-threaded environments
Command parsers for UART/SPI/I2C shells need precise and safe tokenization
Token buffers are often statically allocated in firmware

Solution Logic

Loop through each character
Copy characters into current token until delimiter
On delimiter, terminate current token and move to next row
Handle the last token after loop

101. Split a String Using Delimiter