Converting an array of letter to an array of numbers [closed] - c

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I have a text file in D drive named "data.txt". It has several columns and rows like:
A B A B V B
B V A B A A
B B A A B A
I want to read the "program.txt" file and then convert it to numbers say A=1, B=2, V=3 and then write it so that it will be a array of number. But I'm not sure where to begin. Can someone point me in the right direction?
#include <stdio.h>
int main() {
int n,k;
char C;
FILE *fptr;
fptr=fopen("D:\\program.txt","r+");
printf("Enter n: ");
scanf("%d",&n);
if (n == C){
fprintf(fptr,"%d",3);
}
fclose(fptr);
return 0;
}

Answer 1

From your question, it looks like you want to assign a new number to each character as you encounter it. So you need to keep track of what you've seen and what number was assigned, as well as the current number.
You can do this with an array:
int values[256] = {0};
int next_value = 1;
When you read a character, you can check if you've already seen it. You may also want to check that it's in the right range. If you haven't seen it, assign a number. Otherwise use the number that was originally assigned:
if (c >= 'A' && c <= 'Z') {
if (!values[c]) values[c] = next_value++;
printf ("%d", values[c]);
}
Then it's just a matter of reading the file. There are many ways to do this, but I think the simplest in this case is to read each character from the file in a loop and output them after translating the ones you're interested in:
int c;
while (EOF != (c = getc(fp))) {
if (c >= 'A' && c <= 'Z') {
if (!values[c]) values[c] = next_value++;
printf ("%d", values[c]);
} else {
putchar(c);
}
}

Answer 2

#include <stdio.h>
int main() {
char line_buff[16];
FILE *fptr;
fpos_t pos;
fptr=fopen("D:\\program.txt","r+");
fgetpos(fptr, &pos);
while(fgets(line_buff, sizeof(line_buff), fptr)){//read one line
char *p = line_buff;
while(*p){//convert
if(*p == 'A')
*p++ = '1';
else if(*p == 'B')
*p++ = '2';
else if(*p == 'V')
*p++ = '3';
else
++p;
}
fsetpos(fptr, &pos);
fprintf(fptr, "%s", line_buff);//rewrite
fflush(fptr);
fgetpos(fptr, &pos);//memo position
}
fclose(fptr);
return 0;
}