07 - Predicates and Intro to Loops

07 - Predicates and Intro to Loops - 1 Engineering 101...

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Unformatted text preview: 1 Engineering 101 Predicates and Intro to Loops Quote of the Day - Gandhi It is unwise to be too sure of one's own wisdom. It is healthy to be reminded that the strongest might weaken and the wisest might err. One more bit of selection: Switch Statements n A switch statement is used to decide between a number of cases n switch (integer_expression){ case value: expression case value: expression default: expression } n The integer expression is evaluated and the thread of execution starts from the matching case. If none matches it starts from the default. switch (weekday){ case 1: cout << Monday; break; case 2: cout << Tuesday; break; case 3: cout << Wednesday; break; case 4: cout << Thursday; break; case 5: cout << Friday; break; default: cout << Weekend; } breaks are needed. Otherwise switch drops through to next expression. One more bit of selection: Switch Statements Using operators to construct conditional expressions n Start on some given day. While the day is not a weekend, add 8 hours to my timeclock and work, otherwise rest. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Su M T W Th F Sa 20 21 22 23 24 25 26 27 28 29 30 31 Using operators to construct conditional expressions 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Su M T W Th F Sa 20 21 22 23 24 25 26 27 28 29 30 31 int Sun=0, Mon=1, Tue=2, Wed=3, Thu=4, Fri=5, Sat=6; int firstday= Tue; int timeclock=0, day = 9; firstday tells which day of the week the first day of the month falls upon 2 Using operators to construct conditional expressions 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Su M T W Th F Sa 20 21 22 23 24 25 26 27 28 29 30 31 int Sun=0, Mon=1, Tue=2, Wed=3, Thu=4, Fri=5, Sat=6; int firstday= Tue; int timeclock=0, day = 9; How do we determine whether it is a weekday? Using operators to construct conditional expressions 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Su M T W Th F Sa 20 21 22 23 24 25 26 27 28 29 30 31 int Sun=0, Mon=1, Tue=2, Wed=3, Thu=4, Fri=5, Sat=6; int firstday= Tue; int timeclock=0, day = 9; (firstday+day-1) % 7 != Sun When is the above true? Using operators to construct conditional expressions 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Su M T W Th F Sa 20 21 22 23 24 25 26 27 28 29 30 31 int Sun=0, Mon=1, Tue=2, Wed=3, Thu=4, Fri=5, Sat=6; int firstday= Tue; int timeclock=0, day = 9; while ( (firstday+day-1) % 7 != Sun and (firstday+day-1) % 7 != Sat ) { timeclock = timeclock + 8; cout << Im working. << endl; day = day + 1; } This is only true on weekdays Using operators to construct conditional expressions 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Su M T W Th F Sa 20 21 22 23 24 25 26 27 28 29 30 31 int Sun=0, Mon=1, Tue=2, Wed=3, Thu=4, Fri=5, Sat=6; int firstday= Tue; int timeclock=0, day = 9; while ( (firstday+day-1) % 7 != Sun and (firstday+day-1) % 7 != Sat ) { timeclock = timeclock + 8; cout << Im working. << endl; day = day + 1; } What is the initialization?...
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07 - Predicates and Intro to Loops - 1 Engineering 101...

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