How to output char array in c

Question

Newbiee here, I am trying to scan characters from a txt file and output it to another txt file. I think my problem is conversion specifiers converting int to char so my result is weird characters. Thanks for your help.

#include <stdio.h>
#define NROW 676
#define FILEIN "lettercombo.txt"
#define FILEOUT "lettercomboout.txt"

int main(void) {
//Variables
int i;
char combo [NROW];
FILE *lcombo;
FILE *lcomboout;

//Writes output file or overwrites previous one
lcomboout = fopen(FILEOUT,"w");


// Open file and read data into array
lcombo = fopen(FILEIN,"r");
for (i=0; i<677; i++)
    fscanf(lcombo,"%c",&combo[i]);

for (i=0; i<677; i++)
        fprintf(lcomboout,"%c \n",combo[i]);




return 0;
}

Update post: I forgot to add the input file in the same folder. I appreciate the help, it works :)

Please give(as update post) an example of the output file to be expected and input file. — BLUEPIXY
– BLUEPIXY, Commented Jun 4, 2016 at 0:23
You are reading (via fscanf) integers from input into "combo", which is defined as an array of char... if you want to read "chars" instead of "integer", then change "%i" to "%c". — TonyB
– TonyB, Commented Jun 4, 2016 at 0:32

delta · Accepted Answer · 2016-06-04 01:05:32Z

2

change

fscanf(lcombo,"%i",&combo[i]);

to

fscanf(lcombo,"%c",&combo[i]);

as you scan chars.

change

fprintf(lcomboout,"%c \n",&combo[i]);

to

fprintf(lcomboout,"%c \n",combo[i]);

%c takes a value, not address.

and use fclose to close the file.

UPD

The code reads NROW chars, not NROW lines, change to

for (i=0; EOF != fscanf(lcombo,"%c",&combo[i]); ++i);

or use %s to read lines, it is good manner to check return value of scanf/fscanf.

And you can keep how many chars has been successfully read. For example:

int len;
...
for (len=0; EOF != fscanf(lcombo,"%c",&combo[len]); ++len);
for (i=0; i<len; i++)
    fprintf(lcomboout,"%c \n",combo[i]);

http://en.cppreference.com/w/cpp/io/c/fprintf

edited Jun 4, 2016 at 1:05

answered Jun 4, 2016 at 0:33

delta

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2 Comments

comphonia Over a year ago

thanks, I have applied these changes but still get the weird encoding in my output file with characters like @, $% and spaces.

delta Over a year ago

@comphonia Can you post your input? Is the file utf-8 or other encoding?

BLUEPIXY · Accepted Answer · 2016-06-04 01:19:19Z

0

fix like this:

#define NROW 676 // 26*26 : [A-Z] * [A-Z]
//...
//Variables
int i;
char combo[NROW][2];
//...abridgement
for (i=0; i<NROW; i++)
    fscanf(lcombo," %2c", combo[i]);//fscanf(lcombo," %c%c", &combo[i][0], &combo[i][1]);

for (i=0; i<NROW; i++)
        fprintf(lcomboout, "%c%c\n", combo[i][0], combo[i][1]);

edited Jun 4, 2016 at 1:19

answered Jun 4, 2016 at 1:14

BLUEPIXY

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Comments

Rui Lopes · Accepted Answer · 2016-06-04 00:54:45Z

0

You have 2 errors in your code.

The first one, you figured it out by yourself.

fscanf(lcombo,"%i",&combo[i]);

should be

fscanf(lcombo,"%c",&combo[i]);
The second one is a basic mistake. When you read from the array, you pass arguments by value, not by reference:

fprintf(lcomboout,"%c \n",&combo[i]);

should be

fprintf(lcomboout,"%c \n", combo[i]);.

Both of those mistakes would be easily identified if you had read the warnings sent by the compiler:

main.c: In function ‘main’:
main.c:20:19: warning: format ‘%i’ expects argument of type ‘int *’, but argument 3 has type ‘char *’ [-Wformat=]
     fscanf(lcombo,"%i",&combo[i]);
                   ^
main.c:23:27: warning: format ‘%c’ expects argument of type ‘int’, but argument 3 has type ‘char *’ [-Wformat=]
         fprintf(lcomboout,"%c \n",&combo[i]);
                       ^

Also, it is a good principle is to use the flag -Wall (meaning Warning:all) to compile your code, for example: gcc -Wall my_program.c -o my_program. A lot more warnings will raise.

answered Jun 4, 2016 at 0:54

Rui Lopes

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1 Comment

comphonia Over a year ago

thanks, ill use this flag for future code, I did it well at first but forgot to put the input in the same folder. i appreciate it.

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