Introduction to C Introduction and Hello World Instructor Yin Lou Introduction to C CS - PDF document

AdministriviaIInstructor:YinLou,4144UpsonIEmail:yinlou@cs.cornell.eduILectures:MWF12:20-1:10pm,HLS306IOceHours:TBDIhttp://www.cs.cornell.edu/courses/cs2022/2011sp/ICMS:https://cms.csuglab.cornell.edu IEmailmeyournetidifyouarenotinCMS! IntroductiontoC CS2022,Spring2011,Lecture1 AdministriviaIInstructor:YinLou,4144UpsonIEmail:yinlou@cs.cornell.eduILectures:MWF12:20-1:10pm,HLS306IOceHours:TBDIhttp://www.cs.cornell.edu/courses/cs2022/2011sp/ICMS:https://cms.csuglab.cornell.edu IEmailmeyournetidifyouarenotinCMS! IntroductiontoC CS2022,Spring2011,Lecture1 GoalsICsyntaxIStandardlibrariesIProgrammingforrobustnessandspeedIUnderstandingcompiler IntroductiontoC CS2022,Spring2011,Lecture1 TopicsLect01:IntroductionandHelloWorldLect02:ControlFlowLect03:FunctionsandMakeLect04:PointersandArraysLect05:ComplexTypesLect06:MemoryModelLect07:PerformanceLect08:PreprocessorLect09:StandardInputandOutputLect10:FileandVariable-lengthArgumentListsLect11:ThreadsandSynchronizationLect12:ToBeaMasterProgrammer IntroductiontoC CS2022,Spring2011,Lecture1 EnvironmentIOS:GNU/LinuxIEditor:VimICompiler:gccIDebugger:gdb IntroductiontoC CS2022,Spring2011,Lecture1 IntroductiontoVimI$vimhello.cIi-EntereditingmodeIesc&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0;-Enternormalmode MoreNormalModeCommands I:w-Write/SaveI:q-QuitI:q!-QuitwithoutsavingI:wq-WriteandQuite IntroductiontoC CS2022,Spring2011,Lecture1 IntroductiontoVim MoreCommands ISearchI/+pattern&#x]TJ/;༖ ; .96;& T; 7.;݉ ;� Td;&#x [00;In-nextsearchmatchIN-previoussearchmatchIGotoI:+lineno&#x]TJ/;༖ ; .96;& T; 7.;݉ ;� Td;&#x [00;Igg-GotorstlineIG-GotolastlineIDeleteLineIdd Google\vimcheatsheet"formore! IntroductiontoC CS2022,Spring2011,Lecture1 StructureofaCProgram OverallProgram somepre-processordirectives&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0;globaldeclarations&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0;globalvariables&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0;functions&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0; Functions functionheader&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0;localdeclarations&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0;statements&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0; IntroductiontoC CS2022,Spring2011,Lecture1 StructureofaCProgram OverallProgram somepre-processordirectives&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0;globaldeclarations&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0;globalvariables&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0;functions&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0; Functions functionheader&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0;localdeclarations&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0;statements&#x]TJ/;༖ ;.9;‘ ;&#xTf 8;&#x.485;&#x 0 T; [0; IntroductiontoC CS2022,Spring2011,Lecture1 hello.c:HelloWorld#include&#xstdi;&#xo.h0;intmain(){printf("HelloWorld\n");return0;} IntroductiontoC CS2022,Spring2011,Lecture1 CompilingandRunningI$gcchello.c-ohelloI$./helloHelloWorld IntroductiontoC CS2022,Spring2011,Lecture1 WhatHappens?I$gcchello.c-ohelloICompile\hello.c"tomachinecodenamed\hello"I\-o"speciestheoutputlename.(Noticeit'scase-sensitive.)I$./helloIExecuteprogram\hello"I\./"isnecessay! hello.c #include&#xstdi;&#xo.h0;//"printf"isdeclaredinthisheaderfile.intmain()//Mainpointofexecution.{printf("HelloWorld\n");//Output"HelloWorld"toconsole.return0;//TellOStheprogramterminatesnormally.} IntroductiontoC CS2022,Spring2011,Lecture1 WhatHappens?I$gcchello.c-ohelloICompile\hello.c"tomachinecodenamed\hello"I\-o"speciestheoutputlename.(Noticeit'scase-sensitive.)I$./helloIExecuteprogram\hello"I\./"isnecessay! hello.c #include&#xstdi;&#xo.h0;//"printf"isdeclaredinthisheaderfile.intmain()//Mainpointofexecution.{printf("HelloWorld\n");//Output"HelloWorld"toconsole.return0;//TellOStheprogramterminatesnormally.} IntroductiontoC CS2022,Spring2011,Lecture1 vars.c:Variables#include&#xstdi;&#xo.h0;intmain(){inta,b,c;a=10;b=20;c=a*b;printf("a=%db=%dc=%d\n",a,b,c);return0;} a=10b=20c=200 IntroductiontoC CS2022,Spring2011,Lecture1 vars.c:Variables#include&#xstdi;&#xo.h0;intmain(){inta,b,c;a=10;b=20;c=a*b;printf("a=%db=%dc=%d\n",a,b,c);return0;} a=10b=20c=200 IntroductiontoC CS2022,Spring2011,Lecture1 cmdarg.c:CommandLineArgs#include&#xstdi;&#xo.h0;#include&#xstdl;&#xib.h;intmain(intargc,char**argv){intn,m;n=atoi(argv[1]);m=atoi(argv[2]);printf("Argument1:%d\nArgument2:%d\n",n,m);return0;} $./cmdarg1020Argument1:10Argument2:20 IntroductiontoC CS2022,Spring2011,Lecture1 cmdarg.c:CommandLineArgs#include&#xstdi;&#xo.h0;#include&#xstdl;&#xib.h;intmain(intargc,char**argv){intn,m;n=atoi(argv[1]);m=atoi(argv[2]);printf("Argument1:%d\nArgument2:%d\n",n,m);return0;} $./cmdarg1020Argument1:10Argument2:20 IntroductiontoC CS2022,Spring2011,Lecture1 MoreonprintfIprintf(format string,val1,val2); Iformat stringcanincludeplaceholdersthatspecifyhowtheargumentsval1,val2,etc.shouldbeformattedI%c:formatasacharacterI%d:formatasanintegerI%f:formatasa oating-pointnumberI%%:printa%character Examples floatf=0.95;printf("f=%f%%\n",f*100); f=95.000000% IntroductiontoC CS2022,Spring2011,Lecture1 MoreonprintfIprintf(format string,val1,val2); Iformat stringcanincludeplaceholdersthatspecifyhowtheargumentsval1,val2,etc.shouldbeformattedI%c:formatasacharacterI%d:formatasanintegerI%f:formatasa oating-pointnumberI%%:printa%character Examples floatf=0.95;printf("f=%f%%\n",f*100); f=95.000000% IntroductiontoC CS2022,Spring2011,Lecture1 MoreonprintfIprintf(format string,val1,val2); Iformat stringcanincludeplaceholdersthatspecifyhowtheargumentsval1,val2,etc.shouldbeformattedI%c:formatasacharacterI%d:formatasanintegerI%f:formatasa oating-pointnumberI%%:printa%character Examples floatf=0.95;printf("f=%f%%\n",f*100); f=95.000000% IntroductiontoC CS2022,Spring2011,Lecture1 MoreonprintfIprintf(format string,val1,val2); Iformat stringcanincludeplaceholdersthatspecifyhowtheargumentsval1,val2,etc.shouldbeformattedI%c:formatasacharacterI%d:formatasanintegerI%f:formatasa oating-pointnumberI%%:printa%character Examples floatf=0.95;printf("f=%f%%\n",f*100); f=95.000000% IntroductiontoC CS2022,Spring2011,Lecture1 MoreonprintfIPlaceholderscanalsospecifywidthsandprecisionsI%10d:addspacestotakeupatleast10charactersI%010d:addzerostotakeupatleast10charactersI%.2f:printonly2digitsafterdecimalpointI%5.2f:print1decimaldigit,addspacestotakeup5chars Examples floatf=0.95;printf("f=%.2f%%\n",f*100);//f=95.00%printf("f=%10.2f%%\n",f*100);//f=95.00% IntroductiontoC CS2022,Spring2011,Lecture1 MoreonprintfIPlaceholderscanalsospecifywidthsandprecisionsI%10d:addspacestotakeupatleast10charactersI%010d:addzerostotakeupatleast10charactersI%.2f:printonly2digitsafterdecimalpointI%5.2f:print1decimaldigit,addspacestotakeup5chars Examples floatf=0.95;printf("f=%.2f%%\n",f*100);//f=95.00%printf("f=%10.2f%%\n",f*100);//f=95.00% IntroductiontoC CS2022,Spring2011,Lecture1 WarningaboutprintfIprintfispowerful,butpotentiallydangerous Whatdoesthiscodeoutput? inti=90;floatf=3;printf("f=%fi=%d\n",f);printf("f=%f\n",f,i);printf("i=%df=%f\n",f,i); IntroductiontoC CS2022,Spring2011,Lecture1