An array is a group of memory locations related by the fact that they all have the same name and same type.
int c[12];
This tells the computer to reserve 12 elements for the integer array c. Other examples are:
float a[100], b[23];
char strng[256];
Consider:
int a[5] = {12, 5, 7, 11, 13};
The following table shows that all elements of the array share the same name
a but
each element has a different position number.
|
a[0] |
a[1] |
a[2] |
a[3] |
a[4] |
|
12 |
5 |
7 |
11 |
13 |
Example
#include <stdio.h>
main()
{
float myarray[10];
int i;
myarray[0]=1;
for(i=1;i<10;i++)
{
myarray[i]=myarray[i-1]*(i+1);
}
for(i=0;i<10;i++)
{
printf("%f\n",myarray[i]);
}
}
A string in C is an array of characters ending in the NULL character ( '\0' ). Very similar to numeric arrays we can also declare an array of characters (char).
The declaration:
char sentence[80];
creates an array of 80 characters. It is important that when creating a string that you have enough space in the array to include the NULL character.
A String constant is
a sequence of zero or more characters surrounded by double quotes, for example:
char store[] =
"I am a string";
Note: the size of this array is not specified, when the program is excuted, system will allocate enough space in memory to
hold this string constant.
Remarks: The strcpy function copies strSource,
including the terminating NULL
character, to the location specified by strDestination. No overflow
checking is performed when strings are copied or appended. The behavior of strcpy is
undefined if the source and destination strings overlap.
Remarks: The strcat function appends strSource to strDestination and terminates the resulting string with a NULL character. The initial character of strSource overwrites the terminating NULL character of strDestination. No overflow checking is performed when strings are copied or appended. The behavior of strcat is undefined if the source and destination strings overlap.
#include <string.h>
#include <stdio.h>
void main( void ) {
char string[80];
strcpy(
string, "Hello world from " );
strcat(
string, "strcpy " );
strcat(
string, "and " );
strcat(
string, "strcat!" );
printf(
"String = %s\n", string );
}
Output :
Hello world from strcpy and strcat!
Remarks: Each of these functions returns the number of characters in string, not including the terminating NULL character.
#include <string.h>
#include <stdio.h>
void main( void ) {
char buffer[61] =
"How long am I?";
int
len;
len
= strlen( buffer );
printf(
"'%s' is %d characters long\n", buffer, len
);
}
Output:
'How long am I?' is 14 characters long
For more functions, try command: man string
C communicates with files using a new datatype called a file pointer. This type is defined within stdio.h, and written as FILE *. A file pointer called output_file is declared in a statement like