Assignment OperatorsIncrement and Decrement OperatorsIncrement OperatorPostincrement OperatorPreincrement OperatorCode Example Using ++Decrement OperatorPostdecrement OperatorPredecrement OperatorA Hand Trace ExamplePracticeMore PracticeSlide 13Practice with Assignment OperatorsCode Example Using /= and ++ Counting the Digits in an IntegerDebugging TipsAssignment OperatorsTopicsIncrement and Decrement OperatorsAssignment OperatorsDebugging Tips ReadingSections 3.11 - 3.12Increment and Decrement OperatorsThe increment operator ++The decrement operator --Precedence: lower than (), but higher than * / and %Associativity: right to leftIncrement and decrement operators can only be applied to variables, not to constants or expressionsIncrement OperatorIf we want to add one to a variable, we can say: count = count + 1 ;Programs often contain statements that increment variables, so to save on typing, C provides these shortcuts: count++ ; OR ++count ;Both do the same thing. They change the value of count by adding one to it.Postincrement OperatorThe position of the ++ determines when the value is incremented. If the ++ is after the variable, then the incrementing is done last (postincrementation). int amount, count ; count = 3 ; amount = 2 * count++ ;amount gets the value of 2 * 3, which is 6, and then 1 gets added to count.So, after executing the last line, amount is 6 and count is 4.Preincrement OperatorIf the ++ is before the variable, then the incrementing is done first (preincrementation). int amount, count ; count = 3 ; amount = 2 * ++count ;1 gets added to count first, then amount gets the value of 2 * 4, which is 8.So, after executing the last line, amount is 8 and count is 4.Code Example Using ++#include <stdio.h>int main ( ){ int i = 1 ; /* count from 1 to 10 */ while ( i < 11 ) { printf (“%d ”, i) ; i++ ; /* same as ++i */ } return 0 ;}If we want to subtract one from a variable, we can say: count = count - 1 ;Programs often contain statements that decrement variables, so to save on typing, C provides these shortcuts: count-- ; OR --count ;Both do the same thing. They change the value of count by subtracting one from it.Decrement OperatorPostdecrement OperatorThe position of the -- determines when the value is decremented. If the -- is after the variable, then the decrementing is done last (postdecrementation). int amount, count ; count = 3 ; amount = 2 * count-- ;amount gets the value of 2 * 3, which is 6, and then 1 gets subtracted from count.So, after executing the last line, amount is 6 and count is 2.Predecrement OperatorIf the -- is before the variable, then the decrementing is done first (predecrementation). int amount, count ; count = 3 ; amount = 2 * --count ;1 gets subtracted from count first, then amount gets the value of 2 * 2, which is 4.So, after executing the last line, amount is 4 and count is 2.A Hand Trace ExampleCode Value Answerint answer, garbage = 4; 4 garbagevalue = value + 1 ; value++ ; ++value ; answer = 2 * value++ ; answer = ++value / 2 ; value-- ; --value ; answer = --value * 2 ; answer = value-- / 3 ;PracticeGiven int a = 1, b = 2, c = 3 ;What is the value of this expression? ++a * b - c--What are the new values of a, b, and c?More PracticeGiven int a = 1, b = 2, c = 3, d = 4 ;What is the value of this expression? ++b / c + a * d++What are the new values of a, b, c, and d?Assignment Operators= += -= *= /= %=Statement Equivalent Statementa = a + 2 ; a += 2 ;a = a - 3 ; a -= 3 ;a = a * 2 ; a *= 2 ;a = a / 4 ; a /= 4 ;a = a % 2 ; a %= 2 ;b = b + ( c + 2 ) ; b += c + 2 ;d = d * ( e - 5 ) ; d *= e - 5 ;Practice with Assignment Operatorsint i = 1, j = 2, k = 3, m = 4 ;Expression Valuei += j + kj *= k = m + 5k -= m /= j * 2Code Example Using /= and ++Counting the Digits in an Integer#include <stdio.h>int main ( ){ int num, temp, digits = 0 ; temp = num = 4327 ; while ( temp > 0 ) { printf (“%d\n”, temp) ; temp /= 10 ; digits++ ; } printf (“There are %d digits in %d.\n”, digits, num) ; return 0 ;}Debugging TipsTrace your code by hand (a hand trace), keeping track of the value of each variable.Insert temporary printf() statements so you can see what your program is doing.Confirm that the correct value(s) has been read in.Check the results of arithmetic computations immediately after they are
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