Old Material escape sequences operator precedence printf() scanf() if() switch case &&,|| while, do-while, ++, -- functions New Material 1-D arrays string functions fopen() fclose() fscanf() fprintf()

 Definition: Escape sequences are specially sequenced characters used to format output  \” Ex: printf(“ \ “This is quoted text \ “ “)  \’ Ex: printf(“ \n A single quote looks like \’ \n”);  \* *\ Comment Block

 #include  Using a directive to include a header file  Stdio.h = standard input output header file

 A computer’s long-term memory is called nonvolatile memory and is generally associated with mass storage devices, such as hard drives.  A computer’s short term memory is called volatile memory. It loses is data when power is removed from the computer, such as RAM

To declare a constant (read only) value: const int x = 20 const float PI = 3.14

TYPESIZEVALUES bool1 bytetrue (1) or false (0) char1 byte‘a’ to‘z’, ‘A’ to ‘Z’, ‘0’ to ‘9’, space, tab, and so on int4 bytes-2,147,483,648 to 2,147,483,647 short2 bytes-32,768 to 32,767 long4 bytes-2,147,483,648 to 2,147,483,647 float4 bytes+ - (1.2 x 10^-38 to 3.4 x 10^38) double8 bytes+- (2.3 x 10^-308 to -1.7 x 10^308)

 Can you explain what the code is doing?

 int main() { printf (“%c %c \n", 'a', 65); printf ("%d %ld\n", 1977, L); printf (" %10d \n", 1977); printf ("%010d \n", 1977); printf ("floats: %4.2f \n", ); printf ("%s \n", "A string"); printf(“%f \n”, 55.55); return 0; } }

printf (“%c %c \n", 'a', 65); aA printf ("%d %ld\n", 1977, L); printf (" %10d \n", 1977); 1977 printf ("%010d \n", 1977); printf ("floats: %4.2f \n", ); 3.14 printf ("%s \n", "A string"); A string printf(“%f \n”, 55.55);

 Syntax scanf(“conversion specifier”, variable);

#include main() { int iOperand1 = 0; int iOperand2 = 0; printf(“\n Enter first operand: “); scanf(“%d”, &iOperand1); printf(“\n Enter second operand: “); scanf(“%d”, &iOperand2); printf(“The result is %d \n”, 24/(iOperand1 * iOperand2)+6/3); }

Do you know the answers to these?  A. !( 1 || 0 )  B. !( 1 || 1 && 0 )  C. !( ( 1 || 0 ) && 0 )

 A. !( 1 || 0 ) ANSWER: 0  B. !( 1 || 1 && 0 ) ANSWER: 0 (AND is evaluated before OR)  C. !( ( 1 || 0 ) && 0 ) ANSWER: 1 (Parenthesis are useful)

 Can you write code that will ask a user to enter a number 1, 2, or 3 and print out the following:

int a; int main() { printf (“Enter one of the following: %d, %d, or %d\n”, 1, 2, 3); scanf(“%d”, &a); if(a==1|| a==2|| a ==3) { if(a==1){ printf(“\n %d is the loneliest number \n“, 1); } if(a==2){ printf(“\n%d is better than %d \n”,2,1); } if(a==3){ printf(“\n%d \’ s a crowd \n”,3); } else printf(“Sorry, you entered an invalid value\n”); return 0; } }

 while ( condition ) { Code to execute while the condition is true }  Quiz: Can you write a program that prints x while x increments from 0 to 10?

 do { } while ( condition );  What is the main difference between “Do while” and “while”?

 while ( condition ) { Code to execute while the condition is true }  do { } while ( condition );  Do{} while() executes code at least once!

 How do you generate a new line?  What will happen if a user tries to enter a decimal into scanf(“%d”, &number);  What does each of the following do? *, -, +, /, =, ==, >, <

 Use when the number of iterations is already known  Syntax: for ( variable initialization; condition; variable increment/decrement) { Code to execute while the condition is true }

#include int main() { int x; for ( x = 0; x < 10; x++ ){ printf( "%d\n", x ); } getchar(); }

 Write a program using a FOR Loop to display all of the multiples of 5 from 0 to 100.

#include int main() { int x; for ( x = 0; x < =20; x++ ) { printf( "%d\n", x*5 ); } getchar(); }

x++; x--; Postfix ++x; --x; Prefix main() {int x = 0; int y = 0; printf(“\n The value of y is %d \n”, y++); printf(“\n The value of x is %d \n”, ++x); } Answer: 0 1

 Use to manipulate flow in loops  What does a Break statement do when executed within a loop?  What does a Continue statement do when executed within a loop?

#include main() { int x; for ( x = 10; x >5; x-- ) { if (x==7) break; } printf( “\n %d \n ”, x ); } #include main() { int x; for ( x = 10; x >5; x-- ) { if (x==7) continue; printf( “\n %d \n ”, x ); }

 Function Prototype Syntax return-type function_name ( arg_type arg1,..., arg_type argN )  Function Prototypes tell you the data type returned by the function, the data type of parameters, how many parameters, and the order of parameters  Function definitions implement the function prototype  Where are function prototypes located in the program?  Where do you find function definitions?

 Where are function prototypes located in the program?  Answer: before the main(){} Function!  Function Definitions are self contained outside of the main(){} function

#include int mult ( int, int); int main() { int x; int y; printf( "Please input two numbers to be multiplied: " ); scanf( "%d", &x ); scanf( "%d", &y ); printf( "The product of your two numbers is %d\n", mult( x, y ) ); getchar(); } int mult (int a, int b) {return a * b; }

#include printNumber(); main() { int x; printNumber(x); } printNumber() { printf(“\n The number is %d \n”, x) }

#include void printNumber( int x); main() { int x; printNumber(x); } void printNumber(int y) { printf(“\n The number is %d \n”, y); } *Note: it’s not absolutely necessary to write VOID, but it’s a good practice.

#include void printNumbers(); int iNumber; main() { int x; for(x=0, x<10,x++){ printf(“\n Enter a number:”); scanf(“%d”, &iNumber); printNumbers(); } void printNumbers() { printf(“\n Your number is: %d \n”, iNumber); }

 Variable scope defines the life time of a variable  Local Scope: defined within functions and loses scope after function is finished. Can reuse in other functions (ex. p.123)  Global Scope: defined outside of functions and can be accessed by multiple functions

 Can you write code that asks a user to input 4 integers, adds the numbers together in one function, multiplies them in another, and finally prints out the difference between the sum and product? The user should have to do this 5 times.

#include int addNumbers(int, int, int, int); int multNumbers(int, int, int, int); main() { int a, b, c, d, counter=0; while(counter<6){ printf(“\n Please enter 4 integers separated by spaces\n”); scanf(“%d %d %d %d”, &a, &b, &c, &d); printf(“\n %d \n”, addNumbers(a,b,c,d)-multNumbers(a,b,c,d)); count++; } int addNumbers(int f, int g, int h, int y) { return f+g+h+y; } int multNumbers(int f, int g, int h, int y) { return f*g*h*y; }

 Can you declare a one-dimensional array made up of 10 integers?  Answer: int iArray[10]  How to declare an Array  int iArray[10];  float fAverages[30];  double dResults[3];  short sSalaries [9];  char cName[19]; //18 characters and 1 null character

 Why do we initialize? Because memory spaces may not be cleared from previous values when arrays are created  Can initialize an array directly  Example int iArray[5]={0,1,2,3,4};  Can initialize an array with a loop such as FOR()

#include main() { int x; int iArray[5]; for( x=0; x < 5 ; x++) { iArray[x] = 0; }

 Can you add code to print out the values of the program below? #include main() { int x; int iArray[5]; for( x=0; x < 5 ; x++) { iArray[x] = 0; }

#include main() { int x; int iArray[5]; for( x=0; x < 5 ; x++) { iArray[x] = 0; } for(x=0 ; x<5; x++) { printf(“\n The value of iArray index %d is %d \n”, x, iArray[x]); }

 How do you search through an array?

#include main() { int x; int iValue; int iFound = -1; int iArray[5]; for( x=0; x < 5 ; x++) iArray[x] = (x+x); printf(“\n Enter value to search for:”); scanf(“%d”, &iValue); for(x=0 ; x<5; x++) { if( iArray[x] ==iValue){ iFound =x; break; ) } if(iFound >-1) printf(“\n I found your search value in element %d \n”, iFound); else printf(“\n Sorry, your search value was not found \n”); }

EntityDescription Bit Binary digit, 0 or 1Smallest value in a data file Byte Eight bitsStores a single character FieldGrouping of bytesi.e a word, social security number RecordGrouping of fieldsa single row of information, student name, age, ID, GPA FileGrouping of recordsseparate fields in a record using spaces, tabs, or commas

Please enter how long your name is: 21 Please enter your name: Nawaf Hello Nawaf Please enter how long your name is: -7 Failed allocation memory

int *n; int * n1; n=( int * ) calloc(5, sizeof(int)); // Reserves a block of memory for 5 integers //Decide you need to reallocate more memory later in the program n1= (int *) realloc(n, 10 * sizeof(int));//allocate 10 integers instead of 5 if (n1!=NULL) { n=n1; } else printf("Out of memory!"); realloc() returns null if unable to complete or a pointer to the newly reallocated memory.

Do you know the syntax for each of these, used to read and write to data files?  Pointers: think of it as the memory address of the file  fopen()  fclose()  fscanf()  fprintf()

 fopen() returns a FILE pointer back to the pRead variable #include Main() { FILE *pRead; pRead = fopen(“file1.dat”, “r”); if(pRead == NULL) printf(“\nFile cannot be opened\n”); else printf(“\nFile opened for reading\n”); fclose(pRead); }

 Pretty basic, yet important.

 Reads a single field from a data file  “%s” will read a series of characters until a white space is found  can do fscanf(pRead, “%s%s”, name, hobby);

#include Main() { FILE *pRead; char name[10]; pRead = fopen(“names.dat”, “r”); if( pRead == NULL ) printf( “\nFile cannot be opened\n”); else printf(“\nContents of names.dat\n”); fscanf( pRead, “%s”, name ); while( !feof(pRead) ) { printf( “%s\n”, name ); fscanf( pRead, “%s”, name ); } fclose(pRead); }

Kelly11/12/866Louisville Allen04/05/7749Atlanta Chelsea03/30/9012Charleston Can you write a program that prints out the contents of this information.dat file?

#include main() { FILE *pRead; char name[10]; char birthdate[9]; float number; char hometown[20]; pRead = fopen(“information.dat”, “r”); if( pRead == NULL ) printf( “\nFile cannot be opened\n”); else fscanf( pRead, “%s%s%f%s”, &name[0], birthdate, &number, hometown ); while( !feof(pRead) ) { printf( “%s \t %s \t %f \t %s\n”, name, birthdate, &number, hometown ); fscanf( pRead, “%s%s%f”, name, birthdate, &number, hometown ); } fclose(pRead); }

 The fprintf() function sends information (the arguments) according to the specified format to the file indicated by stream. fprintf() works just like printf() as far as the format goes. printf()

#include main() { FILE *pWrite; char fName[20]; char lName [20]; float gpa; pWrite = fopen(“students.dat”,”w”); if( pWrite == NULL ) printf(“\nFile not opened\n”); else { printf(“\nEnter first name, last name, and GPA separated” printf(“Enter data separated by spaces:”); scanf(“%s%s%f”, fName, lName, &gpa); fprintf(pWrite, “%s \t %s \t %.2f \n”, fName, lName, gpa); } fclose(pWrite); }

 Can you write a program that asks the user for their  Name  Phone Number  Bank account balance And then prints this information to a data file called accounts.dat ?

Good Luck in your final Exam from REACH

 TEXTBOOK RESOURCE: C Programming for the Absolute Beginner 2 nd Edition by Michael Vine 

Kelly11/12/866Louisville Allen04/05/7749Atlanta Chelsea03/30/9012Charleston How many fields are there? How many records are there? How many bytes are there in the first record? How many bits are there in “Kelly”? How many fields are there? How many records are there? How many bytes are there in the first record? How many bits are there in “Kelly”?