How to save strings in the same column to an array from a txt file in C

Question

Suppose I have a txt file that looks like this, where there is only one space between the number and the string:

123 apple

23 pie

3456 water

How can I save apple, pie, and water to an array?

Answer 1

You have a many solutions for this case, i propose some solutions for reading the string from your file:

1. using fscanf, see one example: ``scanf() and fscanf() in C

2. using fgets to read line by line then using ssanf to read the string from each line, see the examples: sscanf() and fgets

For storing the string in an array, you can use the 2D array or the array of char pointer:

char str_array[100][256]; // maximum 100 row and max length of each row ups to 256.
// OR
// You have to allocate for two declarations, and do not forget to free when you do not still need to use them  below
char *str_array[100];
char **str_array;

For copy string to string, you should use strcpy function. Do not use = to assign string to string in c.

For example, i use fscanf:

#include <stdio.h>
#include <string.h>

int main()
{
    FILE *fp = fopen("input.txt", "r");
    if(!fp) {
        return -1;
    }
    char line[256];
    char array[100][256];
    int a, i = 0;
    while(fscanf(fp, "%d %255s",&a, line) == 2 && i < 100) {
        strcpy(array[i], line);
        i++;
    }

    // print the array of string
    for(int j = 0; j < i; j++ ) {
        printf("%s\n", array[j]);
    }
    fclose(fp);
    return 0;
}

The input and output:

#cat input.txt
123 apple
23 pie
3456 water

./test
apple                                                                                                                   
pie                                                                                                                     
water

Answer 2

//This code will read all the strings in the file as described
FILE *fp = fopen("file.txt","r"); //open file for reading
int n = 3;
char *list[n]; //for saving 3 entities;
int i,a;
for(i=0;i<n;i++)
    list[i] = (char *)malloc(sizeof(char)*10); //allocating memory
i = 0;
while(!feof(fp))
    fscanf(fp," %d %s",&a,list[i++]);
printf("%s %s %s\n",list[0],list[1],list[2]);