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Introduction to c part -1

on Mar 28, 2014

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• Printf(“%d”,i) o/p = 11Printf(“%d’,j) o/p = 21
• X=-1,0,1,2
• i=10

Introduction to c part -1Presentation Transcript

• Recall • What is a variable? • How doe the CPU Execution flow occurs? Random or sequential? • What are the options to control the normal flow of executions? • What is a function? When do we use functions?
• Introduction to C Week 2
• How does human perform simple task; for Eg: add 456 and 44 Add 456 and 44 500
• How does human perform simple task; Eg: add 456 and 44 1 We Hear it through our input senses 2 We store the numbers 456 and 44 in our memory 456 44 456+44 3 We calculate the result in our brain and store it in memory 500 3 We say the answer through our output senses
• 1 Computer use keyboard to receive inputs 2 Computer store the numbers 456 and 44 in Ram 456 44 456+44 3 Computer calculate the result in CPU (ALU within CPU) and stores result back in ram 500 4 Computer use monitor to display outputs How does computer perform simple task; Eg: add 456 and 44
• – Start – Get two numbers and store them – Add them and store the result – Print the answer – End Algorithm
• – Start – Get two numbers and store them – Add them and store the result – Print the answer – End Main { int a,b,c; a=456,b=44; c= a+b; // something to print the value from c, will discuss soon } Algorithm Vs Program 500 44 456 b a c
• main() { int a=456, b=44,c; c= a+b; printf (“%d”,c); // So who defined this function?? Where is it located? }
• #include < stdio.h > main() { int a=456, b=44,c; c= a+b; printf (“%d”,c); } ........ Printf(..) { ........ } Scanf (..) {..... } Stdio . h
• Printf() • Printf(“%d”,c) – %d refers to Format specifier which is used to specify the type and format of the data to be taken to the stream and to be printed on screen • %f -> for float data type • %c for Char data type • %s for string data type –c refers to the value of location named c 500 44 456 b a c
• –%d refers to Format specifies which is used to specify the type and format of the data to be retrieved from the stream and stored into the locations pointed by &a. –&a refers to the memory address of location named a scanf()
• Complete Program #include < stdio.h > main() { int a,b,c; Scanf(“%d %d”,&a,&b); c= a+b; printf (“%d”,c); }
• Elements of C • Variables • Operators • Control structures  Decision  Loops • functions
• Variables in C
• Variables int a; Data type variable name
• Variables Data type • Data type is the type of data we are going to store in the reserved Ram location. • We need to specify the data type so that size to be allocated will be done automatically.  Int -> reserves 2 bytes of memory  Char -> reserves 1 byte of memory  float -> reserves 4 bytes of memory Variable Name • Variable is the name we give to access the value from the memory space we allocate. • Variable name should begin with characters or _ ;But
• Variables • Naming a Variable – Must be a valid identifier. – Must not be a keyword – Names are case sensitive. – Variables are identified by only first 32 characters. – Library commonly uses names beginning with _. – Naming Styles: Uppercase style and Underscore style
• Decisions in C
• N Y Start i=1 If i<100 Print iStop Print all the numbers up to 100 i=i+1
• Decisions • Eg: if(i=100) { printf(“You are a low performer”); } else { printf(“You are a top performer”); }
• Nested if • Eg: if(i==0) { printf(“You are a low performer”); } else if(i==200) { printf(“You are a top performer”); } Else if (i==300) { … }
• What is “=“ and “==“ = – As discussed earlier = is used to assign a value into a location we reserved already/or to assign value in to a variable – Eg: a=10 == – Is used to check whether the value of a variable is equal to the value provided in the other side of operand
• switch Switch(i) { Case 0: printf(“poor performer”); break; Case 100: printf(“Good performer”); break; Case default: printf(“performer”); break; }
• switch Switch(i) { Case 0: printf(“poor performer”); break; Case 100: printf(“Good performer”); break; Case default: printf(“performer”); break; } if(i==0) { printf(“Poor Performer”) } else if(i==100) { printf(“Good performer” } Else { Printf(“performer”); }
• Loops in c
• N Y Start i=1 If i<100 Print iStop Print all the numbers up to 100 i=i+1
• Loops in C • For loop • While Loop • Do While Loop
• For Loop for (i=0;i<50;i++) { printf(“%d ”, i); } // {braces} are not necessary if there is only one statement inside for loop Step 1 : i=0 : initialization Step 2 : i<50 : if true step 3 or else step 6 Step 3 : { executes } Step 4 : i++
• While Loop i=0; While(i<50) { printf(“%d ”, i); i++; } // {braces} are not necessary if there is only Step 1 : i=0 : initialization Step 2 : i<50 : if true step 3 or else step 6 Step 3 : { executes } Step 4 : i++
• Do while Loop i=0; Do { printf(“%d ”, i); i++; } While(i<50) Step 1 : i=0 : initialization Step 3 : { executes } Step 4 : i++ Step 2 : i<50 : if true step 3 or
• Other Control statements • Break Statements – The break statement terminates the execution of the nearest enclosing do, for, switch, or while statement in which it appears. • Continue statements – The continue statement works like the break statement. Instead of forcing termination, however, continue forces the next iteration of the loop to take place, skipping
• Example int a = 10; while( a < 20 ) { printf("value of a: %d n", a); a++; if( a > 15) { break; } }
• Example int a = 10; while( a < 20 ) { printf("value of a: %d n", a); a++; if( a > 15) { break; } } Output value of a: 10 value of a: 11 value of a: 12 value of a: 13 value of a: 14 value of a: 15
• Example int a = 10; do { If( a == 15) { a = a + 1; continue; } printf("value of a: %dn", a); a++; } while( a < 20 );
• Example int a = 10; do { If( a == 15) { a = a + 1; continue; } printf("value of a: %dn", a); a++; } while( a < 20 ); Output value of a: 10 value of a: 11 value of a: 12 value of a: 13 value of a: 14 value of a: 16 value of a: 17 value of a: 18 value of a: 19
• Operators • Arithmetic Operators +, - , *, / and the modulus operator %. • Relational operators <, <=, > >=, ==, != • Logical operators &&, ||, ! eg : If (a<10 && b>9) • Assignment Operators =, += ,-= eg: a+=10//same as a=a+10 • Increment and decrement operators
• Difference between i++ and ++i • ++i Increments i by one, then returns i. • i++ Returns i, then increments i by one. i=10,j=20 Z=++i; W=j++; Printf(“%d %d”, z,w); // w=20; z=11
• Questions? “A good question deserve a good grade…”
• Self Check !!
• Self-Check • What is a difference between a declaration and a definition of a variable? – Both can occur multiple times, but a declaration must occur first. – There is no difference between them. – A definition occurs once, but a declaration may occur many times. – A declaration occurs once, but a definition may occur many times. – Both can occur multiple times, but a definition
• Self-Check • What is a difference between a declaration and a definition of a variable? – Both can occur multiple times, but a declaration must occur first. – There is no difference between them. – A definition occurs once, but a declaration may occur many times. – A declaration occurs once, but a definition may occur many times. – Both can occur multiple times, but a definition
• Self-Check • How many times “baabtra“ get printed? main() { int x; for(x=-1; x<=10; x++) { if(x < 5) continue; else break; printf(“baabtra"); } } 1.Infinite times 2.11 Times 3.0 times 4.10 times
• Self-Check • How many times “baabtra“ get printed? main() { int x; for(x=-1; x<=10; x++) { if(x < 5) continue; else break; printf(“baabtra"); } } 1.Infinite times 2.11 Times 3.0 times 4.10 times
• Self-Check What is the output of the following program? void main() { int i=10; switch(i) { case 1: printf(" i=1"); break; case 10: printf(" i=10"); case 11: printf(" i=11"); break; case 12: printf(" i=12"); } } 1. i=10 i=11 i=12 2. i=1 i=10 i=11 i=12 3. i=10 i=11 4. None of above
• Self-Check What is the output of the following program? void main() { int i=10; switch(i) { case 1: printf(" i=1"); break; case 10: printf(" i=10"); case 11: printf(" i=11"); break; case 12: printf(" i=12"); } } 1. i=10 i=11 i=12 2. i=1 i=10 i=11 i=12 3. i=10 i=11 4. None of above
• Self-Check What is the output of the following program? void main() { int i=1,j=1; while (++i < 10) printf("%d ",i); printf("n"); while (j++ < 10) printf("%d ",j); } 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 10
• Self-Check What is the output of the following program? void main() { int i=1,j=1; while (++i < 10) printf("%d ",i); printf("n"); while (j++ < 10) printf("%d ",j); } 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 10
• End of Day 1