Help - string array

Hi,

I have one string as below and would like to change the content one by one. I tried in this way but it's not successed.

Code:

unsigned char newtime[7];

        for (x=7; x>0; x--)
        {    sprintf (newtime[x-1], "%d", x);
              printf ("newtime[%d] %d\n",x, newtime[x-1]);
        }

The console output is:

newtime[6] 0
newtime[5] 0
newtime[4] 0
newtime[3] 0
newtime[2] 0
newtime[1] 0
newtime[0] 0

Where's the problem and what should do?

Thanks.

Wrong forum, yes?
(This is C, not C++.)

you need to assign data to newtime.

not sure what your intentions were for the sprintf call.
<code>
newtime[ 0 ] = 'a';
newtime[ 1 ] = 'b';
newtime[ 2 ] = 'c';
</code>

Sorry if I have posted to a wrong area.

I've been assigned the newtime like this but the content still has not changed:

Code:

unsigned char time[7] = {0x00,0x30,0x09,0x01,0x03,0x00,0x11};

Actually, I want to replace the content of the array with a varable input from terminal.

Thanks.

I'm not sure what you want to achieve but sprintf does not change the value of any individual character. sprintf is actually part of the printf family of functions and works a lot like printf; the only difference is the output is stored as a C-string.

Well, I want to change the time of a RTC IC by input a command line from terminal.

Example:
settime,10,20,30,40,50,60,70

There's an array to store the time information. Example:

Code:

unsigned char time[7] = {0x00,0x30,0x09,0x01,0x03,0x00,0x11};

I use a for loop and the strtok to separate the string into
10
20
30
40
50
60
70

Code:

unsigned char time[7] = {0x00,0x30,0x09,0x01,0x03,0x00,0x11};  // original data
unsigned char newtime[7];
unsigned char * tmp;
int x;

     if (strncmp(uart_tmp, "settime", 7) == 0)  
    {    tmp = strtok(uart_tmp, ",");
        for (x=7; x>0; x--)
        {       tmp = strtok(NULL,",");
                 newtime[x-1] = tmp;
                 printf ("tmp: %s, newtime[%d] %d\n", tmp, (x-1), newtime[x-1]);
        }

When I type in "settime,10,20,30,40,50,60,70":, the output shows:
tmp: 10, newtime[6] 20
tmp: 20, newtime[5] 23
tmp: 30, newtime[4] 26
tmp: 40, newtime[3] 29
tmp: 50, newtime[2] 32
tmp: 60, newtime[1] 35
tmp: 70, newtime[0] 38

Then, how can I repalce the array content with these seven data?

Thanks.

Use strncpy(time, newtime, 7); after all that.

sprintf only outputs C-strings, so in this case it was just not the right function to call, since you are not using a C-string.

Well wait, that's wrong too. Now you've got me doing it.

There's a fundamental problem with what's happening here. A character is just an indivisible piece of data like 'a'. If you went to store a in a character array, you could.

somewhere[ x ] = 'a';

But the string "a" is different. It has to occupy at least two characters in somewhere.

somewhere[ x ] = 'a';
somewhere[ x + 1 ] = '\0';

Likewise for any time you split up a string. You can't munge a "10" into 10 and the like. You would have to convert "10" to an integer and then downcast to char before finally assigning it somewhere.

Wow! Got it after converting the tmp to int before assigning to newtime.

Thanks!