How do i read an array of strings from a file?

Question

I have a file with different words separated by newlines. How can i read and store each word in an array of strings? 1 word, 1 row of the array. I'm posting this code, but im pretty sure it doesnt work, because i can't understand if i should use fgets or fscanf and how i can write each word in each line of my array.

int file_string_temp_number_rows=200;
int file_string_temp_number_cols=200;
char **file_string_arr = (char**)malloc (file_string_temp_number_rows*sizeof(char));

for ( i = 0 ; i < file_string_temp_number_rows ; i++){
    file_string_arr[i] = (char*)malloc(file_string_temp_number_cols*sizeof(char));
}


if ((file_ptr= fopen(filename, "r"))){

    if((file_ptr=fopen(filename,"r"))==NULL)
    {
       printf("errore apertura file");
       return 1;  
    }
    else{
        while(!feof(file_ptr)){
            for(i = 0 ; i < file_string_temp_number_rows ; i++){
                    for(j = 0 ; j < file_string_temp_number ; j++){
                        fgets(file_string_arr , 40 , filename);
                        }
                    }
                }   
            }
        }
    }

Answer 1

Addressing your title question: How do i read an array of strings from a file?

There are many approaches to do this. Here is a list of basic steps that could be used.

1) Using fopen(), open file and scan to determine the following:
- Maximum word length.
- Count of words in file.

2) Create container: - Use calloc() to create an array of strings for words.

3) Using fopen() (again), fgets() and strtok() (or variant) to parse content of file into string array.

Note, The sample implementation snippets below use particular functions and techniques, but you should not limit your implementation to only these. There are many paths that would work just as well, so do not be afraid to experiment. For example, either fgets() or fscanf() could be used to solve this problem. The methods highlighted below are just examples of one way to do the task.

Scan example

// provides count of words, and longest word

int longestWord(char *file, int *nWords)
{
    FILE *fp=0;
    int cnt=0, longest=0, numWords=0;
    char c;
    fp = fopen(file, "r");
    if(fp)
    {

     // if((strlen(buf) > 0) && (buf[0] != '\t') && (buf[0] != '\n') && (buf[0] != '\0')&& (buf[0] > 0))

        while ( (c = fgetc(fp) ) != EOF )
        {
            if ( isalnum (c) ) cnt++;
            else if ( ( ispunct (c) ) || ( isspace(c) ) || (c == '\0' ))
            {
                (cnt > longest) ? (longest = cnt, cnt=0) : (cnt=0);
                numWords++;
            }
        }
        *nWords = numWords;
        fclose(fp);
    }
    else return -1;

    return longest;
}

//in main eg:
int longest;
int count;
...
longest = longestWord(".\\file.txt", &count);//longest and count will be 
                                             //used to create string arrays

Create string array example

//Create string arrays to contain words using result from original scan of file
char ** Create2DStr(ssize_t numStrings, ssize_t maxStrLen)
{
    int i;
    char **a = {0};
    a = calloc(numStrings, sizeof(char *));
    for(i=0;i<numStrings; i++)
    {
      a[i] = calloc(maxStrLen + 1, 1);
    }
    return a;
}
// in main(): Create array of words
char **words = Create2DStr(count, longest);//Using values obtained from scan section above
if(words) { //continue

Parse into word strings example

// in main(), after performing scan and array creation:
const char delim[] = {" \n\t"};
char line[260];
char *buf = NULL;

fp = fopen(".\\file.txt", "r");
cnt=0;
while(fgets(line, 260, fp))//keep reading lines until EOF
{
    buf = strtok(line, delim);
    while(buf)//continue until last word in line is parsed
    {    
        if((strlen(buf) > 0) 
        {
            strcpy(words[cnt], buf);
            cnt++; //use as accurate count of words.
        }
        buf = strtok(NULL, DELIM);
    }
}
fclose(fp);