Discovering C !

What C compiler should I use?

2006-08-18T19:16:00.000+05:30

The Harbour developers consider GNU GCC to be the supported compiler of the Harbour project, use of the GCC port for your chosen platform is encouraged.

However, should you wish to use a different C compiler your contribution to make it work is more than welcome. Currently the following C compiler and platform combinations are supported by someone in the development team:

Microsoft Windows
- GCC (CYGWIN)
- GCC (MINGW32)
- Borland C/C++ 4/5/Builder (their free compiler works)
- Microsoft Visual C++ 10/11/12
- IBM Visual Age for C++
DOS 32bit
- GCC (DJGPP)
- Watcom C/C++
DOS 16bit
- Borland C/C++ 3.1
GNU/Linux
- GCC (various versions).
OS/2
- GCC (EMX)
- IBM C++
Macintosh
- MPW

C @@ my Notes

2006-07-13T01:25:00.000+05:30

A string constant is a character array terminated by a null ('\0').

For EG:

char name[]={'R', 'T', 'L', 'i', 'n', 'u', 'X', '\0'};

Each character in the array occupies one byte of memory and last character is always '\0'. It looks like two characters but actually is just one. It is different from 0. The ascii value of 0 is 48 where as ascii value of \0 is 0.

Three ways write a C program for strings:

METHOD 1

#include

main()

{

char os[]="Suse";

int i=0;

while (i<=5)

{

printf("%c",os[i]);

i++;

}

printf("\n");

return 0;

}

METHOD 2

#include

main()

{

char os[]="Redhat";

int i=0;

while(os[i]!='\0')

{

printf("%c",os[i]);

i++;

}

printf("\n");

return 0;

}

METHOD 3

#include

main()

{

char os[]="Debian";

char *i=os;

//i=os;

while(*i!='\0')

{

printf("%c",*i);

i++;

}

printf("\n");

return 0;

}

METHOD 4

#include

main()

{

char os[]="Ubuntu";

printf("%s",os);

printf("\n");

return 0;

}

METHOD 5

#include

main()

{

char os[15];

printf("\nPlease enter the name of the Operating System: ");

scanf("%s",os);

printf("%s",os);

printf("\n");

return 0;

}

Note the declaration char os[15] sets aside 15 bytes under the the array os[], where as the scanf function fills in the characters typed at keyboard into this array until the enter key is hit. Once the enter key is hit, the scanf() places a '\0' in the array.

The length of string should not exceed the character array dimension because C compiler doesn't perform bounds checking on character array.

scanf is not capable of receiving multi-word strings. Hence to use multi word strings use gets(). Counter part of gets() is puts(). puts() can display only one string at a time.

EG:

#include

main()

{

char os[15];

printf("Please enter the name of os: ");

gets(os);

puts("Use ");

puts(os);

puts("\n");

return 0;

}

scanf can be made to accept multi word strings as shown in following example:

EG:

#include

main()

{

char os[15];

printf("Please enter the oss which u like: ");

scanf("%[^\n]s",os);

printf("You love %s", os);

printf("\n",os);

return 0;

}

Suppose we wish to store “Hello”. We may either store it in string or we may ask the C compiler to store it at some location in memory and assign the address of the string in a char pointer. This is shown bellow.

#include

main()

{

char os1[]="Xandros";

char os2[10];

os2=os1;

printf("%s",os2);

printf("\n");

return 0;

}

#include

main()

{

char lang1[]="vb.net";

char *lang2;

lang2=lang1;

printf("%s",lang2);

printf("\n");

return 0;

}

STANDARD LIBRARY FUNCTIONS:

Function	Use
strlen	Finds length of a string.
strupr	Converts a string to upper case.
strlwr	Converts a string to lower case.
strcat	Appends one string at the end of other string.
strncat	Appends n characters at the end of other string.
strcpy	Copies one string at the end of other string.
strncpy	Copies first n characters at the end of other string.
strcmp	Compares two strings without ignoring the case.
strncmp	Compares first n characters of two strings.
stricmp	Compares two strings ignoring the the case.
strnicmp	Compares first n characters of two strings ignoring the case.
strdup	Duplicates the string.
strrev	Reverses the string.
strstr	Finds first occurance of given string in other string.
strchr	Finds first occurance of given characters in other string.
strrchr	Finds last occurance of given characters in other string.
strset	Sets all characters of a given string in another string.
strnset	Sets first n characters of a string to a given character.

#include

main()

{

char os1[]="goose";

char os2[]="Solaris";

int l1;

int l2;

l1=strlen(os1);

l2=strlen(os2);

printf("%s has a length of %d", os1,l1);

printf("\n");

printf("%s has a length of %d", os2,l2);

printf("\n");

return 0;

}

#include

main()

{

char os1[]="server2003";

int ln1,ln2;

ln1=cstrlen(os1);

ln2=cstrlen("serverNT");

printf("%s has a length of %d",os1,ln1);

printf("\n");

printf("%s has a length of %d","serverNT",ln2);

printf("\n");

return 0;

}

cstrlen(char *s)

{

int l3=0;

while(*s!='\0')

{

l3++;

s++;

}

return(l3);

}

#include

main()

{

char mp[]="xmms";

strupr(mp);

printf("%s",mp);

printf("\n");

return 0;

}

#include

main()

{

char edi1[]=" Open Office ";

char edi2[50]="Word is not better than";

strcat(edi2,edi1);

printf("%s", edi2);

printf("\n");

return 0;

}

#include

main()

{

char mp[]="AMORK";

strlwr(mp);

printf("%s",mp);

printf("\n");

return 0;

}

#include

main()

{

char edi1[]=" Open Office ";

char edi2[50]="Word is not better than";

strcat(edi2,edi1);

printf("%s", edi2);

printf("\n");

return 0;

}

#include

main()

{

char unixfather[50];

char linuxfather[]="Linux Torvalds owes many things to Denis Ritchie";

strcpy(unixfather,linuxfather);

printf("%s \n", unixfather);

printf("%s \n", linuxfather);

return 0;

}

#include

main()

{

char intking1[50];

char intking2[50]="Google is giving a run for money to Yahoo";

cstrcpy(intking1,intking2);

printf("%s \n",intking1);

printf("%s \n",intking2);

return 0;

}

cstrcpy(char *add1,char *add2)

{

//*int i=0;

while(*add2!='\0')

{

*add1=*add2;

add1++;

add2++;

}

//*add1=*add2;

//return(add1);

}

By declaring char as constant we are declaring that the source string should remain constant(should not change). Thus the const qualifier ensures that your program does not inadvertently alter a variable that you intended to be a constant.

strcmp()

This is a function which compares two strings to find out whether they are same or different. The two strings are compared character by character until there is a mismatch or end of one of the strings is reached, which ever occurs first. If two strings are identical, strcmp returns a value zero. If they are not it returns numeric difference of ascii values of the first non matching pairs of characters.

ARRAYS

EG1:

#include

main()

{

int i;

int a[]={2,4,5,6,7,8,8};

for(i=0;i<7;i++)

display(a[i]);

printf("\n");

return 0;

}

display(int m)

{

printf(" %d",m);

}

EG2:

#include

main()

{

int i;

int ary[]={1,2,3,4,5,6};

for(i=0;i<6;i++)

display(&ary[i]);

printf("\n");

}

display(int *n)

{

show(&n);

//printf("%c",n);

}

show(int *m)

{

int *l;

l=*m;

printf("%d",*l);

printf("\n");

}

See my C!

2006-02-15T11:24:00.000+05:30

The Sea of C!
C needs no introduction. No matter you do what in computers or IT field, you should know C Language. In fact C is the building block of all other Languages. If you know C, you would be in a position to grasp all other Languages very easily. Also all major applications are designed in C. Take for instance entire Linux is designed and programmed using C Language. Same is the case with Oracle. In fact older versions of Windows were also programmed in C. In every interview you would be asked questions on C Language. There is no substitute and rescue for C. The bottom line is you need to know C. The sea of C is very big. Earlier you learn to swim in this sea, better it gets for you.

History of C!
C is a programming language that was developed at AT & T’s Bell Laboratories of USA in 1972. It was developed by Denis Ritchie. In late seventies C began to replace other familiar languages of that time like ALGOL, PL/I, FORTRAN etc and even new languages of that time like PASCAL, APL etc. C has continued its domination even today.

Why you should learn C?

To understand other higher programming languages much easily like C, C++, VC++, C#, Shell Scripting, Java etc.
To go into the dept of how an operating system and various applications works you need to know C because all major operating systems like Unix, Linux, Older versions of Windows etc are being written in C. Applications like Oracle are also being designed in C.
Most of the device drivers are written in C.
It is always an advantage to develop a Game in C, because for games it’s the speed with which your game runs counts. And when it comes to speed, nothing beats C.
Speed and efficiency are also very important for gadgets like Mobiles, PDAs etc because they have to work fast and that too in limited amount memory available. Hence Programmers love to write the Operating system pertaining to these devices in C.

The C Character Set:
Alphabets: A, B, C………………….Z
a , b, c , …………………z
Digits: 1, 2 , 3,……………………….10
Special Symbols: ~ ` ! @ # $ % ^ & * ( ) _ - + = | \ { } [ ] : ; “ ‘ < > , . ? /

Constants, Variables and Keywords:
Constant: A constant is an entity that doesn’t change.
Variable: It is an entity that may change.

Rules for Constructing Integer Constants

1. An integer constant must at least contain on digit.

2. It must not have a decimal point.

3. It can be either possitive or negetive.

4. If no sign precedes an integer constant it is assumed to be possitive.

5. No commas or blank spaces are allowed within an integer constant.

6. The allowable range for integer constants is -32768 to 32767.

Swiming in C

2006-01-29T15:43:00.000+05:30

C is mother of Languages !!