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Published byAbraham Chambers Modified over 9 years ago
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PHY 107 – Programming For Science
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Announcements no magic formulas exist Need to learn concepts: no magic formulas exist Single solution not useful; will not see problem again Examples from slides/web cannot just be copied What does scanf do? When should it be used? How to print out things? What does %lf mean? Project #1 available later tonight; due in 3 weeks You will complete 3 larger projects over term Tie everything together; more realistic problems solved DO NOT LEAVE FOR LAST MOMENT
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Today’s Goals At end of lecture, be able to use if statements Choose what is executed so not just calculator Understand source of many bugs & how to avoid Correctly use braces ( { } ) and make code pretty Be able to explain when & why if s used
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Boolean Values 3 boolean functions can combine into computer Billions of gates combined by engineers to make CPU (a && b) || (a && !c) Could use, for example: (a && b) || (a && !c) But how to generate inputs for these functions First need boolean values of true and false Easy in hardware (true is any signal > 3.3V) But how could we do get values within our program?
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Boolean Operators AND && (“AND”: true when both operands true) OR || ( “OR”: true when either operand true) XOR ^ ( “XOR”: true when only one operand true) NOT ! ( “NOT”: true when operand false)
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Relational Operators < ( less than) > ( greater than) <= ( less than of equal to) >= ( greater than of equal to) != ( inequality ≠) == ( equality – if two things have same value) NOT the same as assignment (=)
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Relational Operators
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< ( less than) > ( greater than) <= ( less than of equal to) >= ( greater than of equal to) != ( inequality ≠) == ( equality – if two things have same value) NOT the same as assignment (=)
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Code Structures in Programming Sequence
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Code Structures in Programming Sequence Decision true false
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if (…) statement 1 st evaluates boolean expression in parenthesis Executes next statement if expression is true When expression is false, skips past statement(s) int num = -32; if (num = 0)) { printf(" "); } if (num >= 0) { printf("%lf=square root of %d", sqrt(num), num); }
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if (…) statement
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I Want More!
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A Modest Proposal
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Spacing in a Program C/C++ ignores almost all spaces in a program This also means where most newlines placed ignored Symbolic constants & text in quotes are exceptions This can lead to some very… interesting code
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What Does This Compute? char _3141592654[3141 ],__3141[3141];_314159[31415],_3141[31415];main(){register char* _3_141,*_3_1415, *_3__1415; register int _314,_31415,__31415,*_31, _3_14159,__3_1415;*_3141592654=__31415=2,_3141592654[0][_3141592654 -1]=1[__3141]=5;__3_1415=1;do{_3_14159=_314=0,__31415++;for( _31415 =0;_31415<(3,14-4)*__31415;_31415++)_31415[_3141]=_314159[_31415]= - 1;_3141[*_314159=_3_14159]=_314;_3_141=_3141592654+__3_1415;_3_1415= __3_1415 +__3141;for(_31415 = 3141- __3_1415 ;_31415;_31415--,_3_141 ++,_3_1415++){_314 +=_314<<2 ;_314<<=1;_314+= *_3_1415;_31 =_314159+_314; if(!(*_31+1) )* _31 =_314 / __31415,_314 [_3141]=_314 % __31415 ;* ( _3__1415=_3_141 )+= *_3_1415 = *_31;while(* _3__1415 >= 31415/3141 ) * _3__1415+= - 10,(*--_3__1415 )++;_314=_314 [_3141]; if ( ! _3_14159 && * _3_1415)_3_14159 =1,__3_1415 = 3141-_31415;}if( _314+(__31415 >>1)>=__31415 ) while ( ++ * _3_141==3141/314 )*_3_141--=0 ;}while(_3_14159 ) ; { char * __3_14= "3.1415"; write((3,1) (--*__3_14,__3_14 ),(_3_14159 ++,++_3_14159))+ 3.1415926; } for ( _31415 = 1; _31415<3141- 1;_31415++)write( 31415% 314-( 3,14),_3141592654[ _31415 ] + "0123456789","314" [ 3]+1)-_314; puts((*_3141592654=0,_3141592654)) ;_314= *"3.141592";}
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Indentation Traditionally we indent code within braces ( {} ) Use consistent size to indent (I use 2 spaces)
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Indentation Traditionally we indent code within braces ( {} ) Use consistent size to indent (I use 2 spaces) Nothing is
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Indentation Traditionally we indent code within braces ( {} ) Use consistent size to indent (I use 2 spaces) Nothing is more
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Indentation Traditionally we indent code within braces ( {} ) Use consistent size to indent (I use 2 spaces) Nothing is more annoying
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Indentation Traditionally we indent code within braces ( {} ) Use consistent size to indent (I use 2 spaces) Nothing is more annoying than
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Indentation Traditionally we indent code within braces ( {} ) Use consistent size to indent (I use 2 spaces) Nothing is more annoying than looking
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Indentation Traditionally we indent code within braces ( {} ) Use consistent size to indent (I use 2 spaces) Nothing is more annoying than looking for
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Indentation Traditionally we indent code within braces ( {} ) Use consistent size to indent (I use 2 spaces) Nothing is more annoying than looking for the next
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Indentation Traditionally we indent code within braces ( {} ) Use consistent size to indent (I use 2 spaces) Nothing is more annoying than looking for the next line.
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Your Turn Get in groups & work on following activity
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For Next Lecture Friday Read pages 99 – 104 for Friday What if we want to have multiple possible options? How do else & else if statements work? We will have lab on Thursday weekly assignment due tomorrow Week #3 weekly assignment due tomorrow If problem takes more than 10 minutes, TALK TO ME!
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