Question

I was hoping if you can help me with some input and 2 dimensional arrays for this method of a program I am writing for an assignment. The programming language is C I got some input parameters:

FILE * ifp = input file pointer, opened up in main, opened a txt file with a format of 3 strings per line

char ** firstTokens, middleTokens = 2 dimensional char arrays, I want them to hold the first two strings minus expected punctuation at the end of each string (such as commas and periods). Planned to be an output parameter.

char * lastLetter = The first letter of whatever string is in the last column per line in the txt file. Planned to be an output parameter.

int numberOfLines = number of lines I’m expecting to read from the text file

This is the call to the method in my main function:

readLine(ifp, firstTokens, middleTokens, lastLetter, numberOfLines);

I think my problem is with getting the firstTokens and middleTokens correctly, as I’m always getting compiler errors and segmentation faults in my edits. Some help/clarifications to the errors would be greatly appreciated.

void readLine(FILE * ifp, char ** firstTokens, char ** middleTokens, char* lastLetter, int numberOfLines)
{
    char* tempFirst;
    char* tempMiddle;
    char* tempLast;
    char delim[4];
    delim[0] = '.';
    delim[1] = '\0';
    delim[2] = '\n';
    delim[3] = ',';
    int i;

    for(i = 0; i < numberOfLines; i++)
    {
        fscanf(ifp, "%s %s %s", tempFirst, tempMiddle, tempLast);
        *firstTokens[i] = strtok(tempFirst, delim);
        *middleTokens[i] = strtok(tempMiddle, delim);
        lastLetter[i] = tempLast[0];
    }
}

Answer 1

You’ll need to allocate storage for tempFirst, tempMiddle, and tempLast. fscanf writes to these pointers, assuming you’ve provided sufficient memory at them.

#define MAX_NAME_LEN (20) /* change this as required */
...
char tempFirst[MAX_NAME_LEN];
char tempMiddle[MAX_NAME_LEN];
char tempLast[MAX_NAME_LEN];
...
fscanf(ifp, "%s %s %s", tempFirst, tempMiddle, tempLast);