CODEWITHSUNDEEP
c
user1390048
user1390048

Reputation: 141

Reading columns from a text file in C

I have a text file with 100 rows and 512 columns, each column is separated by a tab:

row1    00  00  20  00  11  00  00  00  00  10
        00  11  00  55  77  00  00  70  21  00
        90  ...

I would like to read through each row and store value in each column in an array.

I dont want to use sscanf and separate the variables, as it requires creating another 500 variables.
If I use fgets, I can get the whole line, but how do I separate columns with spaces and store them in an array?

Thanks.

Upvotes: 2

Views: 2490

Answers (3)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726599

You can use strtok_r, a reentrant version of strtok, to separate elements of a string into tokens. You can call strtok_r in a loop, call atoi on each token, and add tokens to the array for the row.

strtok_r has a usage pattern that is nearly identical to that of strtok, but it has an extra parameter to represent the current state of the tokenizer. Regular strtok keeps that state in the static memory, making the function non-re-entrant.

const char *term = "\t\n\r "; // word terminators
char str[] = "quick brown fox jumps over the lazy dog";
char *state; // Invocation state of strtok_r
char *tok = strtok_r(str, term, &state); // First invocation is different
while (tok) {
        printf("%s\n", tok);
        tok = strtok_r(NULL, term, &state); // subsequent invocations call with NULL
}

Upvotes: 4

Tiago Peczenyj
Tiago Peczenyj

Reputation: 4623

you can use strtok

http://www.cplusplus.com/reference/clibrary/cstring/strtok/

and iterate over each word

Upvotes: 1

Nashibukasan
Nashibukasan

Reputation: 2028

I believe you could use a string tokenizer with a tab delimiter. Here is an example.

Upvotes: 1

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