Lecture 02 C Strings and File IO
h functions that can be used for this task. printf is used for standard output while scanf is used for standard input. Writing output to STDOUT. Let us
5. ?tení dat ze souboru
Funkce fscanf() se používá podobným zp?sobem jako scanf() Konverze %c slouží pro na?tení znaku (do prom?nné typu char).
Práce se soubory v jazyku C
Nov 2 2011 fopen
Functions scanf and EOF
The return of scanf In C++ bool represents boolean value
C library function fscanf()
C LIBRARY FUNCTION - FSCANF. Description. The C library function int fscanfFILE ? stream constchar ? format
Writing to and reading from files
fscanf() has a file pointer that tells where where the input should be In C writing and reading files is one of the places where errors that can.
Snímek 1
Na?tení všech ?ísel ze souboru data.txt uloženého na disku C soubor = fopen('C:\data.txt' 'r'); cisla = fscanf(soubor
Pole dynamická alokace pam?ti
v jazyce C je možnost definovat prvky for(i=0;i<n;i++) scanf("%d"&A[i]); ... vícerozm?rné pole je v jazyce C uloženo po ?ádcích ...
C library function - scanf()
The C library function int scanfconstchar ? format . . . reads formatted input from stdin. Declaration. Following is the declaration for scanf function.
Ficheros Manejo de ficheros en C Apertura del fichero Apertura del
La función fscanf lee los datos del fichero indicado por su primer parámetro (en vez de leerlos del teclado). int fscanf( FILE *f char formato[]
C Strings and I/O Strings I/O Parsing 1 - Virginia Tech
Reading C-strings: fscanf() Suppose we want to read personal names from an input file and we are told each line of the input file will obey the following formatting rule: < > MariontMitchelltMorrison For example: But how long might one of those strings be? We have three possibilities:
CC LLIIBBRRAARRYY FFUUNNCCTTIIOONN -- FFSSCCAANNFF
fscanf type specifiers type Qualifying Input Type of argument c Single character: Reads the next character If a width different from 1 is specified the function reads width characters and stores them in the successive locations of the array passed as argument No null character is appended at the end char *
Quick and Dirty Guide to C - University of Washington
int c[2][3]; //c is an array of 2 arrays of three ints a[1][0] follows a[0][2] Array variables (e g abc above) cannot be made to point to other arrays Strings are represented as character arrays terminated by ASCII zero Pointers are indicated by left associative asterisk (*) in the type declarations: int a*a; // a is a pointer to an integer
I/O in C - Colorado State University
Standard C Library • I/O commands are not included as part of the C language • Instead they are part of the Standard C Library •A collection of functions and macros that must be implemented by any ANSI standard implementation •Automatically linked with every executable •Implementation depends on processor operating system etc
Lecture 04 - Pointers and Strings - CMU School of Computer
We can create a file stream using an input file as follows: FILE* fp = fopen(“myfile txt””r”); The file is now open for “r” only and fp (FILE* or FILE pointer) can be used to read input from the file A major function to use is fscanf You can find more about fscanf using: man fscanf
C Reference Card (ANSI) Constants Flow of Control Program
c 1999 Joseph H Silverman Permissions on back v1 3 Constants long (su x) L or l oat (su x) F or f read from le fscanf(fp"format"arg1:::) close le fclose(fp)
ECE160: Foundations of Computer Engineering I
fscanf(file_pointer “format_string” address_list) The input file indicated by the file_pointer Should have an acceptable file name Must be linked with a file_pointerusing fopen() before it is used Should be closed after it is used fclose(file_pointer); FILE*file_pointer; file_pointer = fopen(“file_name” “r”); FILE file_pointer
Programming in C - pearsoncmgcom
The C programming language provides four other basic data types: float double char and _Bool A variable declared to be of type float can be used for storing floating-point numbers (values containing decimal places) The double type is the same as type float only with roughly twice the precision
Getting Input From the User by Using scanf Page 1
The scanf function takes as its arguments: A format string that consists of format specifiers of the form blah separated by spaces where blah is typically one of: i – to input an int (i e signed integer); equivalently you can use d for this f – to input a float (i e single-precision floating-point number)
C - PROGRAMMING
In C – Programming the fscanf function is used to read formatted input from a stream Syntax: Sample Code: getch(); fscanf (FILE *stream const char *format );
Standard library I/O
The sscanf() function operates in a manner similar to fscanf() but (as we saw in processing command line arguments) instead of consuming data from a file it will consume data from a memory resident buffer Like fscanf() it returns the number of items it successfully consumed from the buffer
Contents
The fscanf() Command The fscanf() command is more generally applicable and can be used to read in many different types of data from any ASCII text file The general form of fscanf() is as follows: array = fscanf(fileID‘format specifiers’[colsrows]) Where array is any valid variable name
Searches related to fscanf c filetype:pdf
fscanf type specifiers type Qualifying Input Type of argument c Single character: Reads the next character If a width different from 1 is specified the function reads width characters and stores them in the successive locations of the array passed as argument No null character is appended at the end char *
CReferenceCard(ANSI)
ProgramStructure/Functions
typefnc(type1,:::)functiondeclarations typenameexternalvariabledeclarations main(){mainroutine declarationslocalvariabledeclarations statements typefnc(arg1,:::){functiondenition declarationslocalvariabledeclarations statements returnvalue; /**/comments main(intargc,char*argv[])mainwithargs exit(arg)terminateexecutionCPreprocessor
includelibraryle#includeExample.#definemax(A,B)((A)>(B)?(A):(B))
undene#undefname quotedstringinreplace# concatenateargsandrescan## isnamedened,notdened?#ifdef,#ifndef namedened?defined(name) linecontinuationchar\DataTypes/Declarations
character(1byte)char integerint oat(singleprecision)float oat(doubleprecision)double short(16bitinteger)short long(32bitinteger)long positiveandnegativesigned onlypositiveunsigned pointertoint,float,:::*int,*float,::: enumerationconstantenum constant(unchanging)valueconst declareexternalvariableextern registervariableregister localtosourcelestatic novaluevoid structurestruct createnamebydatatypetypedeftypename sizeofanobject(typeissize_t)sizeofobjectInitialization
initializevariabletypename=value initializearraytypename[]={value1,:::} initializecharstringcharname[]="string" c long(sux)Lorl oat(sux)Forf exponentialforme octal(prexzero)0 hexadecimal(prexzero-ex)0xor0X characterconstant(char,octal,hex) a \ooo \xhh newline,cr,tab,backspace\n,\r,\t,\b specialcharacters\\,\?,\ stringconstant(endswith \0 )"abc:::de"Pointers,Arrays&Structures
declarepointertotypetype*name genericpointertypevoid* nullpointerNULL objectpointedtobypointer*pointer addressofobjectname&name arrayname[dim] multi-dimarrayname[dim1][dim2]:::Structures
structtag{structuretemplate declarationsdeclarationofmembers createstructurestructtagname memberofstructurefromtemplatename.memberExample.(*p).xandp->xarethesame
singlevalue,multipletypestructureunion biteldwithbbitsmember:bOperators(groupedbyprecedence)
structurememberoperatorname.member structurepointerpointer->member increment,decrement++,-- plus,minus,logicalnot,bitwisenot+,-,!,~ castexpressiontotype(type)expr sizeofanobjectsizeof multiply,divide,modulus(remainder)*,/,% add,subtract+,- left,rightshift[bitops]<<,>> comparisons>,>=,<,<= comparisons==,!= bitwiseand& bitwiseexclusiveor^ bitwiseor(incl)| logicaland&& logicalor|| conditionalexpressionexpr1?expr2:expr3 assignmentoperators+=,-=,*=,::: expressionevaluationseparator, statementterminator; blockdelimeters{} exitfromswitch,while,do,forbreak nextiterationofwhile,do,forcontinue gotogotolabel labellabel: returnvaluefromfunctionreturnexprFlowConstructions
ifstatementif(expr)statement elseif(expr)statementelsestatement whilestatementwhile(expr) statement forstatementfor(expr1;expr2;expr3) statement dostatementdostatementwhile(expr); switchstatementswitch(expr){ANSIStandardLibraries
CharacterClassTests
alphanumeric?isalnum(c) alphabetic?isalpha(c) controlcharacter?iscntrl(c) decimaldigit?isdigit(c) lowercaseletter?islower(c) printingcharacter(inclspace)?isprint(c) uppercaseletter?isupper(c) hexadecimaldigit?isxdigit(c) converttolowercase?tolower(c) converttouppercase?toupper(c) StringOperations
s,tarestrings,cs,ctareconstantstrings lengthofsstrlen(s) copycttosstrcpy(s,ct) uptoncharsstrncpy(s,ct,n) concatenatectaftersstrcat(s,ct) uptoncharsstrncat(s,ct,n) comparecstoctstrcmp(cs,ct) onlyrstncharsstrncmp(cs,ct,n) pointertorstcincsstrchr(cs,c) pointertolastcincsstrrchr(cs,c) copyncharsfromcttosmemcpy(s,ct,n) comparencharsofcswithctmemcmp(cs,ct,n) putcintorstncharsofcsmemset(s,c,n) 123CReferenceCard(ANSI)
Input/Output
StandardI/O
standardinputstreamstdin standardoutputstreamstdout standarderrorstreamstderr endofleEOF getacharactergetchar() printacharacterputchar(chr) readlinetostrings(CodesforFormattedI/O:"%-+0w:pmc"
-leftjustify +printwithsign spaceprintspaceifnosign0padwithleadingzeros
wmineldwidth pprecision mconversioncharacter: hshort,llong,Llongdouble cconversioncharacter: d,iintegeruunsigned csinglecharscharstring fdoublee,Eexponential ooctalx,Xhexadecimal ppointernnumberofcharswritten g,Gsameasfore,EdependingonexponentVariableArgumentLists
lastargislastnamedparameterofthefunction absolutevalueofintnabs(n) absolutevalueoflongnlabs(n) quotientandremainderofintsn,ddiv(n,d) quotientandremainderoflongsn,dldiv(n,d) pseudo-randominteger[0,RAND_MAX]rand() setrandomseedtonsrand(n) terminateprogramexecutionexit(status) passstringstosystemforexecutionsystem(s) Conversions
convertstringstodoubleatof(s) convertstringstointegeratoi(s) convertstringstolongatol(s) convertprexofstodoublestrtod(s,endp) same,butunsignedlongstrtoul(s,endp,b)StorageAllocation
changesizeofobjectrealloc(pts,size) deallocatespacefree(ptr)ArrayFunctions
TimeandDateFunctions
processortimeusedbyprogramclock() currentcalendartimetime() time structuretypeforcalendartimecompstm tm_secsecondsafterminute tm_minminutesafterhour tm_hourhourssincemidnight tm_mdaydayofmonth tm_monmonthssinceJanuary tm_yearyearssince1900 tm_wdaydayssinceSunday tm_ydaydayssinceJanuary1 tm_isdstDaylightSavingsTime ag convertlocaltimetocalendartimemktime(tp) converttimeintptostringasctime(tp) convertcalendartimetoGMTgmtime(tp) tpisapointertoastructureoftypetm MathematicalFunctions
Argumentsandreturnedvaluesaredouble
trigfunctionssin(x),cos(x),tan(x) arctan(y=x)atan2(y,x) exponentials&logsexp(x),log(x),log10(x) division&remaindermodf(x,*ip),fmod(x,y) powerspow(x,y),sqrt(x) constantsona32-bitUnixsystem.CHAR_BITbitsinchar(8)
CHAR_MAXmaxvalueofchar(127or255)
CHAR_MINminvalueofchar(128or0)
INT_MAXmaxvalueofint(+32,767)
INT_MINminvalueofint(32,768)
LONG_MAXmaxvalueoflong(+2,147,483,647)
LONG_MINminvalueoflong(2,147,483,648)
SCHAR_MAXmaxvalueofsignedchar(+127)
SCHAR_MINminvalueofsignedchar(128)
SHRT_MAXmaxvalueofshort(+32,767)
SHRT_MINminvalueofshort(32,768)
UCHAR_MAXmaxvalueofunsignedchar(255)
UINT_MAXmaxvalueofunsignedint(65,535)
USHRT_MAXmaxvalueofunsignedshort(65,536)
FloatTypeLimits
FLT_RADIXradixofexponentrep(2)
FLT_ROUNDS
oatingpointroundingmodeFLT_DIGdecimaldigitsofprecision(6)
FLT_EPSILONsmallestxso1:0+x6=1:0(105)
FLT_MANT_DIGnumberofdigitsinmantissa
FLT_MAXmaximum
oatingpointnumber(1037)FLT_MAX_EXPmaximumexponent
FLT_MINminimum
oatingpointnumber(1037)FLT_MIN_EXPminimumexponent
DBL_DIGdecimaldigitsofprecision(10)
DBL_EPSILONsmallestxso1:0+x6=1:0(109)
DBL_MANT_DIGnumberofdigitsinmantissa
DBL_MAXmaxdouble
oatingpointnumber(1037)DBL_MAX_EXPmaximumexponent
DBL_MINmindouble
oatingpointnumber(1037)DBL_MIN_EXPminimumexponent
May1999v1.3.Copyrightc
1999JosephH.Silverman
allcopies. 456quotesdbs_dbs14.pdfusesText_20
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