1. Cs288 Intensive Programming in Linux
Instructor: C F Yurkoski
Section web site:
Class 6
6-9-15

2. Topics today
Homework revu
More C
Time for questions

3. text
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4. Submit only .c files (or .h if I ask for header files too.)
Insure that your code compliles on the afs Linux using the default options (no –gcc)
Write a hello world program – done in class last week
Do problem 1-4 from text
Do problem 1-8 from text

5. First program
/* This is a comment */ #include <stdio.h> /* preproc d*/ main() { printf("hello world\n"); }
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6. Problem 1-4 Exercise 1-4. Write a program to print the corresponding Celsius to Fahrenheit table.

8. Problem 1-8: ite a program to count blanks, tabs, and newlines.
./public_html/x/exer1-8A.c

10. Some more Basics of C
6-9-15

11. Conditional Operator ? : exp1 ? exp2 : exp3
If exp1 is non-zero value of expression is exp2 otherwise it is exp ? 2 : 3
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14. Operator Precedence left to right
* / %
+ -
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15. Some Basics
/* Comments */ { blocks } Parameters ( ) # preprocessor directive Statements end with ; Loops: for while Conditionals if then
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16. $ cat header. h #define ROOT 1 $ cat main1. c /. This is a multi-line
$ cat header.h #define ROOT 1 $ cat main1.c /* * This is a multi-line * comment block. */ #include <srdio.h> #include "header.h" /* This a one line comment */ main(){ int x=ROOT; /* this is an embeeded comment */ #ifdef ROOT printf("%d",x); #else printf("not root\n"); #endif }

17. $ cc main1.c $ ./a.out 1$

18. Basic printf formats %i or %d int %c char %f float %s string
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19. Width and precision %d print as decimal integer
at least 6 characters wide
%f print as floating point
%6f print as floating point, at least 6
characters wide
%.2f print as floating point, 2 characters after
decimal point
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20. I/O
C=getchar();
putchar(C);
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21. for statement
for(init;condition;increment) { statement(s); } for(i=0;i<5;i++) printf(“%d\n”,i);
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22. Symbolic Contants #define name replacement text #define LIMIT 30
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23. Escape sequences \a 07 Alarm (Beep, Bell) \b 08 Backspace
\f 0C Formfeed
\n 0A Newline (Line Feed)
\r 0D Carriage Return
\t 09 Horizontal Tab
\v 0B Vertical Tab
\\ 5C Backslash
\‘ 27 Single quotation mark
\“ 22 Double quotation mark
\? 3F Question mark
\nnn any The character whose numerical value is given by nnn interpreted as an octal number
\xhh any The character whose numerical value is given by hh interpreted as a hexadecimal number
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24. if statement
if ( expression) statement else if ( expression ) else if ( expression )
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25. arrays
int myarray[10];
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26. functions
int function ( int param1, char param2); … int function ( int param1, char param2) { int local1, local2; /* call by value */ retval=function2 (local1); return(10); }
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27. argv, argc
#include <stdio.h> int main (int argc, char *argv[]) { printf(“%s\n”,argv[0]); return 0; }
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28. compiler
cc file.c –o file
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29. More basic C More on arrays:
Array initialization during declaration: int num[5];
num[0]=1;
int num[5]={1,2,3,4,5};
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30. Multi-dimensional arrays
int a[2][3]; int a[2][3]={{1,2,3},{4,5,6}};
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31. Multi-dimensional arrays cont
#include <stdio.h> main() { int a[2][3]={{1,2,3},{4,5,6}}; int i,j; for(i=0;i<2;i++) for(j=0;j<3;j++) printf("a[%d][%d]=%d\n",i,j,a[i][j]); }
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32. Multi-dimensional arrays cont
afsconnect1-58 >: ./a.out a[0][0]=1 a[0][1]=2 a[0][2]=3 a[1][0]=4 a[1][1]=5 a[1][2]=6
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33. Strings are just arrays of characters.
#include <stdio.h> main() { char name1[25]="NJIT"; char name2[25]={'N','J','I','T','\0'}; printf("name1=%s\n",name1); printf("name2=%s\n",name2); } >: ./a.out name1=NJIT name2=NJIT
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34. Strings (cont).
main() { char name1[25]="NJIT"; char name2[25]={'N','J','I','T','\0'}; char *name3="NJIT"; printf("name1=%s\n",name1); printf("name2=%s\n",name2); printf("name3=%s\n",name3); } afsconnect1-67 public_html >: ./a.out name1=NJIT name2=NJIT name3=NJIT
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35. Strings (cont).
Header file string.h Some examples: strcmp String Compare strcat String Concatenation memcpy Copy Memory Block strlen String Length
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36. General form: Strcat(string1,string2) Appends string2 to string1;
Strings (cont).
General form: Strcat(string1,string2) Appends string2 to string1;
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37. Addresses! & used to get the address of a variable main() { int i=666;
printf("i= %d\n",i);
printf("&i= %d\n",&i); }
afsconnect1-72 public_html >: ./a.out
i= 666
&i=
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38. More C keywords
switch break, continue, goto sizeof Storage classes: auto register extern static
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39. switch( Grade ) { case 'A' : printf( "Excellent\n" ); case 'B' : printf( "Good\n" ); case 'C' : printf( "OK\n" ); case 'D' : printf( "Mmmmm....\n" ); case 'F' : printf( "You must do better than this\n" ); default : printf( "What is your grade anyway?\n" ); }
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40. label: while (true) { if(a) break; if(b) continue; if(c) goto label; }
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41. printf("sizeof i= %d\n",sizeof(i)); printf("sizeof array= %d\n",
main() {
int i=666;
char array[15];
double n;
printf("sizeof i= %d\n",sizeof(i));
printf("sizeof array= %d\n",
sizeof(array));
printf("sizeof n= %d\n", sizeof(n)); }
>: ./a.out
sizeof i= 4
sizeof array= 15
sizeof n= 8
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42. static Has number of implications:
Local static variables initialized only once and retain their value.
Guaranteed to be automatically initialized to zero if not otherwise initialized.
Global static variable inaccessible outside the file.
Can be applied to functions.
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43. Structures!
struct <name> { element1; element2; … }
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44. Structures example
struct class { char name[30]; int number; char instructor[25]; int students[35]; };
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45. Structures element dereferencing
structure-variable.stucture-member; e.g.: x=class.number;
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46. Arrays of Structures
struct class semester[30]; struct grades { char name[30]; int id; int grades[10]; }g[35];
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47. Unions
struct class semester[30]; union students { long x; char grades[8]; }g[35];
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48. sizeof can be applied to unions and structures
Structures can be nested.
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49. Pointers
General form: datatype *ptrname; int x=666, y=555; Int *p; p = &x; y = *p;
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50. Some cc command line options
Compiling multiple C files.
Linking multiple objects.

51. $ cat main. c main(){ func(); } $ cat sub. c func(){} $ cc main
$ cat main.c main(){ func(); } $ cat sub.c func(){} $ cc main.c /tmp/ccRFdyU8.o: In function `main': main.c:(.text+0xa): undefined reference to `func' collect2: error: ld returned 1 exit status $ cc sub.c /usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/crt1.o: In function `_start': (.text+0x20): undefined reference to `main' $ cc main.c sub.c $ cc -c main.c $ cc -c sub.c $ cc main.o sub.o $ cc main.c sub.o $

52. $ cat main. c #include "tmp. h" main(){ func(); } $ cc -c main. c main
$ cat main.c #include "tmp.h" main(){ func(); } $ cc -c main.c main.c:1:17: fatal error: tmp.h: No such file or directory ^ compilation terminated. $ ls -l /tmp/tmp.h -rw-rw-r--. 1 integration integration 0 Mar 3 09:23 /tmp/tmp.h $ cc -c -I /tmp main.c $

53. Homework Do exercise 1-19 from the text.
Write a program which reads stdin and converts any local case characters to upper case.
Redo problem 4 from class 2 as a C program.
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54. problem 4
Write a C program, sort.c, which sorts a list of command line parameters in ascending order. For example, your command will look something like:  $ sort and type enter. Your program will return:
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