【leetcode】697. 数组的度

char * defangIPaddr(char * address){
    int len = strlen(address);
    char* s = (char*)calloc(sizeof(char), len*2);
    char* buffer;
    buffer = strtok(address, ".");
    while (buffer){
        strcat(s, buffer);
        buffer = strtok(NULL, ".");
        if (buffer == NULL)
            break;
        strcat(s, "[.]");    
    }
    return s;
}