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scanf problem

Ahmed saleh

Hi, im trying to do an SMS project using AT Commands , i wanna display what the mobile sends on LCD , something like when i write the correct AT command using printf("AT\r"); it gives OK , i wanna display that OK on LCD , so i used scanf to capture the message from the mobile but it doesnt work, it freezes the display.
here is my code so far


char array[20];
lcd_com(0XC0);
lcd_puts("SMS Project");
DELAY_Second();
DELAY_Second();
DELAY_Second();
DELAY_Second();
DELAY_Second();
DELAY_Second();
lcd_com(0x01);
while(1){

 printf("AT\r");
 scanf("%s",&array);
 PC_LINK_IO_Send_String(&array);
 lcd_puts(array);


}


void lcd_puts(char *aaa){
unsigned int i=0;
for(;aaa[i]!=0;i++)lcd_data(aaa[i]);
}
}

  • 0

    Careful with scanf! It can be lethal - especially when scanning for strings. Can you tell me how scanf() would be able to know the size of your array, and what would happen if the received data doesn't fit?

    In Keil you can use gets() to get a text line. For most other environments, you should instead look for fgets(). It is important that always (!) make sure that your program can't overwrite any buffers.

    By the way - you do know that the name of an array is the same as the pointer to the first element in the array?

    Another thing: What would happen if you manage to call lcd_puts() with a malformed string not containing a terminating zero? How many characters would then be written?

  • 0 in reply to ImPer Westermark

    Thanks so much for your help


    By the way - you do know that the name of an array is the same as the pointer to the first element in the array?

    Yea , i do know that.


    What would happen if you manage to call lcd_puts() with a malformed string not containing a terminating zero? How many characters would then be written?


    Dont know , but the Mobile phone sends always OK or error with a \r at the end , so what do i've to change ?

  • 0 in reply to Ahmed saleh

    No, that's not true.

    The phone - and, in fact, any other modem - might be echoing your commands and will also be sending some additional "formatting" characters.

    See my post of 22-May-2008 10:44 in the following thread, and follow the links:

    http://www.keil.com/forum/docs/thread12482.asp