正确使用Malloc和免费使用C ++指针

Question

Sorry if this question comes across as trying to take the easy way out, but I really think I just need some clarification. I'm trying to use malloc and free. I thought I understood them, but the assignment itself that I'm doing them for is somewhat confusing.

Each element in the tklist array is supposed to point to an individual token (set of characters either between quotes or separated by spaces). So, I need to allocate the space and then also free it.

What I don't understand is when the memory is supposed to be freed. I've tried freeing it in all sorts of places and nothing works. I think I just don't fully understand something, and I've looked up malloc and free extensively for the last couple of days trying to figure it out.(Maybe I'm supposed to free in my main? maybe my strncpy is wrong?) Any help would be really appreciated!

Here is the function, it takes as parameters an array of characters and an array of char pointers and returns as its answer the number of tokens that were found in the first parameter. The function should parse the tokens and add each one in turn to the tklist array.

int parseCommandLine(char cline[], char *tklist[]){
    int i;
    int length;
    int count = 0; //counts number of tokens
    int toklength = 0; //counts the length of each token
    length = strlen(cline);
    for (i=0; i < length; i++) {   //go to first character of each token

        if (((cline[i] != ' ' && cline[i-1]==' ') || i == 0)&& cline[i]!= '"') {



            while ((cline[i]!=' ')&& (cline[i] != '\0') && (cline[i] != '\r')){
                toklength++;
                i++;
            }
        count ++;
          //---------------
        //tklist[count] = (char *) malloc( toklength +1);
        //strncpy(tklist[count], &cline[i], toklength);
          //  free( (void *)tklist[count] );
         //--------------

            toklength = 0;
        }
        //--------------
        //free( (void *)tklist[count] );
        //--------------
        if (cline[i] == '"') {
            do {
                toklength++;
                i++;
                if (cline[i] == ' ') {
                    toklength--;
                }
            } while (cline[i]!='"');
            count++;
            //--------------
            //tklist[count] = (char *) malloc( toklength +1);
            //strncpy(tklist[count], &cline[i], toklength);
            //free( (void *)tklist[count] );
            //--------------
            toklength = 0;
        }
        //--------------
        //free( (void *)tklist[count] );
        //--------------
    }
    cout << count;
    return count;



}

Answer 1

使用完后，您需要在调用方释放tklist。