Thread: Finding the ASCII value of a string?

Can't see anything wrong with that. Have you tried specifying a specifc path, e.g.

Code:

fopen("c:\\mydir\\reformated.txt","w+");

Note the double backslashes.

So, if you run this on a directory you can't write in [or create new files in] , it will crash, since you don't check that buff and reformat are valid files after fopen();

Code:

fprintf(buff,"%c",(char)found[b]);

This is a longer way of saying

Code:

fputc(found[b], buff);

--
Mats

Originally Posted by Nicheter

Would

Code:

if((reformed = fopen(argv[1], "r+"))==NULL) {
                        printf("Read Only Directory\n");
                        Sleep(500);
                        exit(1);

Resolve this issue?

I don't think that's an appropriate error message. If argv[1] is an absolute path containing directories which don't exist, then the problem is not a "Read Only Directory," but a directory which simply doesn't exist in the first place. Secondly, whether a directory is "read only" does not necessarily have anything to do with whether a file itself is "read only."

Originally Posted by Nicheter

Would

Code:

if((reformed = fopen(argv[1], "r+"))==NULL) {
                        printf("Read Only Directory\n");
                        Sleep(500);
                        exit(1);

Resolve this issue?

Ehm, you bashed that up quickly, right? You can't open reformed as an input ("r+") with argv[1] as the name... ;-)

And of course the error could be MANY things (for example out of memory, disk full, directory full, etc), so either use strerror()/perror() or just say "Can't open output file" would be the right thing.

--
Mats

Whoops!
should be

Code:

if((reformed = fopen("c:\\reformatted.txt", "w+"))==NULL) {
                        printf("Error Creating Output File!\n");
                        Sleep(500);
                        exit(1);

Well, that always happens when I execute the code, that is, I get "Error Creating Output File!" on stdout.

Code:

#include <stdio.h>

int main(void)
{
	FILE* reformed;
	if((reformed = fopen("c:\\reformatted.txt", "w+"))==NULL) 
	{
		printf("Error Creating Output File!\n");
		return 1;
	}

	printf("Success\n");
	return 0;
}

I run this program and got "Success" (both first time, when the file does not exists, and second time - when the file already exists)

Do you have disk c:?
Is file not locked by other application?

Yeah, I figured it out. I accidentally added a character to the if statement. Thanks guys! '
EDIT: Continuing in the vein of not wanting to start a new thread, somewhat related to this one, I need help with strcmp. I have a list of input strings and each one corresponds to a number. Other than writing the function, as i have in the past,(using musical notes and their frequencies)

Code:

if(strcmp(a,"a"==0)){
 return 440.000;
}
if (strcmp(a,"ad"==0)){
 return 220.000;
}
if (strcmp(a,"au"==0)){
 return 880.000;
}

etc. this gets somewhat tedious after a while...

Presumably,

Code:

if(strcmp(a,"a"==0)){

->

Code:

if(strcmp(a,"a")==0){

Anyway. If you feel like hard-coding everything, you might be able to use something like this -- basically an extension of matsp's and my idea above.

Code:

struct {
    const char *name;
    double hertz;
} data[] = {
    {"a", 440.000},
    {"ad", 220.000},
    {"au", 880.000}
};
size_t x;

for(x = 0; x < sizeof(data) / sizeof(*data); x ++) {
    if(!strcmp(note, data[x].name)) {
        return data[x].hertz;
    }
}

If you're not familiar with structures, you could use two parallel arrays. For example:

Code:

const char *note[] = {"a", "ad", "au", ...};
double hertz[] = {440.000, 220.000, 880.000, ...};

Of course, you might be better off actually calculating those values instead of hard-coding them. I'm sure there's a formula for it. I researched this once, but I've forgotten what I discovered, if anything . . . .

Ah, thanks! Calculating the values may be worth researching, otherwise the Structure would be best (I was going to try and learn it soon anyways)
For the record, the formula seems to be (using A below middle C)

Code:

F = {[(2)^1/12]^n} * 220 Hz

Where:

	F = the frequency of the pitch
	n = the number of half-steps up from "A" the pitch lies

Which is nice, and makes this slightly easier

Ok, easiest way is to use only one array, due to the formula working in half-steps, setting the initial value to that of low C means that I can use the position of the array when it evaluates as the number of half-steps from low C. Trying to run this it executes, but no output is heard...
edit: Yeah, silly mistake, i used the wrong variable... What would be a safe way to get note from the user? scanf isn't good for this, it's pretty easily broken.

Code:

#include <string.h>
#include <stdlib.h>
#include <windows.h>
double getfreq(char *note);

int main()
{
    char *note="c";
    double frequency;
    frequency=getfreq(note);
    Beep(frequency,100);
    return(0);
}
double getfreq(char *note)
{
       const char *name[]={"cd","csd","dd","dsd","ed","fd","fsd","gd","gsd","ad","asd","bd"..........,"cuu"};
       int i,n;
       double f;
       for (i=0;i<37;i++)
       {
           if (!strcmp(note,name[i]))
           {
              f=(((2)^(1/12))^i)*130.813;
              return(f);
           }
       }
       return(0);
}

Code:

f=(((2)^(1/12))^i)*130.813;

This most likely doesn't do ANYTHING like what you want it to do, since ^ is "bitwise exclusive or", not "x to the power of y". To do that, you need "pow()".

--
Mats

Originally Posted by matsp

Code:

f=(((2)^(1/12))^i)*130.813;

This most likely doesn't do ANYTHING like what you want it to do, since ^ is "bitwise exclusive or", not "x to the power of y". To do that, you need "pow()".

--
Mats

Hmm, really? It seemed like it worked, but I'll try that.
EDIT, yeah, it doesn't work, but how does pow take arguments?
edit2: ah, rewritten as

Code:

f=pow(pow(2,(1/12)),i)*130.813;

Originally Posted by Nicheter

Hmm, really? It seemed like it worked, but I'll try that.

If you don't care what notes you get, then it probably sort of works, but it will give you a pretty random output, rather than one where you get the correct note you want. Try printing the values it gives you.

--
Mats