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Superman
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| working with functions |
 Posted: Mon Mar 30, 2009 5:54 pm |
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I am using a function to read a keypad. Then I want to send the value read in my main function. If make the function return a char to main. In main I can then send this char.
But I keep getting
"a numeric expression must appear here! at the this instruction in the main
char z;
pls find the attached code below thanks
| Code: |
#include<16f873.h>
#use delay(clock = 4000000)
#fuses xt, nolvp, nowdt
#include<lcd_driver_code.c>
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, parity=E, BITS=8, stream=PIC)
#define B1 Pin_B1
#define B2 pin_B2
#define B3 pin_B3
char keypad_read_display(void){ //function definition/declaration
char k;
int value;
output_low(B1); output_high(B2); output_high(B3);
value=input(pin_b4)+(input(pin_b5)*2)+(input(pin_b6)*4)+(input(pin_b7)*8);
switch(value){
case 0XF: break;
case 0XE: k = '1'; break;
case 0XD: k = '4'; break;
case 0XB: k = '7'; break;
case 0X7: k = '*'; break;
default: }
output_high(B1); output_low(B2); output_high(B3);
value=input(pin_b4)+(input(pin_b5)*2)+(input(pin_b6)*4)+(input(pin_b7)*8);
switch(value){
case 0XF: break;
case 0XE: k = '2'; break;
case 0XD: k = '5'; break;
case 0XB: k = '8'; break;
case 0X7: k = '0'; break;
default: }
output_high(B1); output_high(B2); output_low(B3);
value=input(pin_b4)+(input(pin_b5)*2)+(input(pin_b6)*4)+(input(pin_b7)*8);
switch(value){
case 0XF: break;
case 0XE: k = '3'; break;
case 0XD: k = '6'; break;
case 0XB: k = '9'; break;
case 0X7: k = '\#'; break;
default: }
//printf(lcd_putc,"\f %c", key);
}
main(char){
lcd_init();
set_tris_b(0XFF);
port_b_pullups(TRUE);
char z;//i get error at this line, numeric constant must appear
char k;
while(1){
keypad_read_display();
putchar(z);
delay_ms(100);}}
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon Mar 30, 2009 6:14 pm |
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main() doesn't take any parameters in this compiler. There is no argc
and argv. Don't assume that everything in MSVC is transportable to CCS.
| Quote: | main(char){
lcd_init();
set_tris_b(0XFF);
port_b_pullups(TRUE);
char z;//i get error at this line, numeric constant must appear
char k; while(1){
keypad_read_display();
putchar(z);
delay_ms(100);}} |
Don't put variable declarations within code, with this compiler. Put them
at the start of a function. In this case, they go above the lcd_init() line.
| Quote: | | If make the function return a char to main |
You need to buy a book on C and study how a function returns a value
to the caller. It's not really our job to teach this. This forum is about
teaching the oddities of the CCS compiler (amongst other things).
It's assumed that you know basic C. |
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Guest
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| Posted: Mon Mar 30, 2009 6:22 pm |
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Thank you.
I moved the putchar into function and it works now.
Points noted |
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