® #define PI 3.142 float area; int square (int r); /* My first C program */ main() { printf(“Hello world!”); 23 tells the compiler to include the source code from the file ‘stdio.h’ into the program. The extension .h stands for header file. A header file contains information about standard functions that are used in the program. The header file stdio.h which is called the STandar D Input and Output header file, contains most of the input and output functions. It is necessary to use only the include files that pertain to the standard library functions in your program. /* My first C program / is a comment in C. Tradional comments are preceded by a /* and end with a */. Newer style comments begin with // and go to the end of the line. Comments are ignored by the compiler and therefore do not affect the speed or length of the compiled code. #use rs232(baud=9600,xmit=PIN_B0 rs232(baud=9600,xmit=PIN_B0,rcv=PIN_B1) ,rcv=PIN_B1) main() { printf(“Enter characters:”); while(TRUE) putc(toupper(getc())); } tell the preprocessor to look in predefined include file directories for the file, while the quote marks tell the preprocessor to look in the current directory first. #include “thatfile.h” value defines the name you will use throughout your program, value is the value you are assigning to . #define TRUE 1 #define pi 3.14159265359 return value; } main() { double result; result = sqrt(16.0); printf(“%f\n”,result); } } Notice that the declaration is divided into two parts. Only the names of parameters are included inside the parenthesis. Outside of the parenthesis the data types and formal parameter names are specified.>b a=a&b a=a|b a=a^b void main(void) { char str[10]; strcpy(str, “Motoroloa who?”); printf(str); } functions char string[10]; . struct s_type { int i; char str[80]; } s,*p; void main(void) { p=&s; s.i=10; p->i=10; strcpy(p->str,”I strcpy(p->str,”I like structures”); printf(“%d %d %s”,s.i,p->i,p->str); %s”,s.i,p->i,p->str); }
