Transfer results to txt file C - c

Question

so i'm completely new to programming (i've been learning for 3 days) and i find myself infront of a problem i simply don't know how to resolve.
I want this program to give me every single combination from 0 to a specific number in base 36. That is easy enough when the number is only about 50000 or so. But my goal from this is to extract actual words(with numbers too) and if i try to get words with 5 characters, the terminal will start overwriting the previous words(not helpful, i want ALL of them).
So i thought i should look for a way to transfer everything into a txt file and there resides my problem: I don't know how... Sorry for the long text but i wanted to explain precisely what i'm trying to get. Thanks for the help.
int main() {
int dec, j, i, q, r, k;
char val[80];
printf("Enter a decimal number: ");
scanf("%d", &dec);
for (k = 0; k <= dec; k++) { /*repeat for all possible combinations*/
q = k;
for (i = 1; q != 0; i++) { /*convert decimal number to value for base 36*/
r = q % 36;
if (r < 10)
r = r + 48;
else
r = r + 55;
val[i] = r;
q = q / 36;
}
for (j = i - 1; j > 0; j--) { /*print every single value*/
printf("%c", val[j]);
}
printf(" "); /*add spaces because why not*/
}
return (0);
}

Answer 1

A few observations that might help:
First is type related:
In your declarations you create the following:
int dec, j, i, q, r, k;
char val[80];
Then later you make the assignment:
val[i] = r;//assigning an int to a char, dangerous
While r is type int with a range (typically) of –2,147,483,648 to 2,147,483,647,
val[i] is of type char with a range (typically) of only –128 to 127.
Because of this, you may run into an overflow, leading to unexpected results.
The most immediate solution is use the same type for both variables. Pick either int or char, but not both.
The other has already been addressed correctly by #Nasim. Use the file version of printf() - fprintf(). As the link shows, the prototype for fprintf() is:
int fprintf( FILE *stream, const char *format [, argument ]...);
Usage example:
FILE *fp = fopen(".\somefile.txt", "w");//create a pointer to a FILE
if(fp)//if the FILE was successfully created, write to it...
{
// some of your previous code...
for (j = i - 1; j > 0; j--)
{ /*print every single value*/
fprintf(fp, "%c", val[j]);//if val is typed as char
//OR
fprintf(fp, "%d", val[j]);//if val is typed as int
}
fclose(fp);
}
Lastly, there are a wide range of methods to perform base conversion. Some more complicated than others.

Answer 2

create a file and then you can use fprintf() instead of printf the only difference between the two is that you need to specify the file as an argument
FILE *myFile = fopen("file.txt", "w"); //"w" erase previous content, "a" appends
If(myFile == NULL) {printf("Error in openning file\n"); exit(1);}
fprintf(myFile, "some integer : %d\n", myInteger); // same as printf my specify file pointer name in first argument
fclose(myFile); //dont forget to close the file