如何使用C中的函数从字符串中仅提取数字？

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

void extractNumbers(const char* str, int* numbers, int* count) {
    int len = strlen(str);
    int numCount = 0;
    int numStart = -1;
    int i;

    for (i = 0; i < len; i++) {
        if (isdigit(str[i])) {
            if (numStart == -1) {
                numStart = i;
            }
        } else {
            if (numStart != -1) {
                int numLen = i - numStart;
                char* numStr = (char*)malloc((numLen + 1) * sizeof(char));
                strncpy(numStr, &str[numStart], numLen);
                numStr[numLen] = '\0';
                numbers[numCount++] = atoi(numStr);
                free(numStr);
                numStart = -1;
            }
        }
    }

    if (numStart != -1) {
        int numLen = len - numStart;
        char* numStr = (char*)malloc((numLen + 1) * sizeof(char));
        strncpy(numStr, &str[numStart], numLen);
        numStr[numLen] = '\0';
        numbers[numCount++] = atoi(numStr);
        free(numStr);
    }

    *count = numCount;
}

int main() {
    const char* str = "abc123def456ghi789";
    int numbers[10];
    int count;

    extractNumbers(str, numbers, &count);

    printf("Extracted numbers: ");
    for (int i = 0; i < count; i++) {
        printf("%d ", numbers[i]);
    }
    printf("\n");

    return 0;
}