Bismillah hiir Rehman nir Raheem-----------------------------Assalat o Wasalam o Alika Ya RasoolALLAH
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Chapter 3 Expressions and Interactivity
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Some operating systems limit the number of files that may be open at one time. When a program closes fil es that are no longer being used, it will n Ot deplete more of the operating system's resources than necessa ry.
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Calling the file strea m object's close member funct ion closes a fi le. Here is an example:
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QutputFile.close();
Writing Data to a File
You alread y know how to use t he strea m insertion operator «<) w ith the cout o bject to
write data to t he screen . It can a lso be used with fil e stream objects to write data to a file.
outputFile «
"I love c+ + programming";
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Assuming outputFile is a file stream object, the fo llowing statement demonstrates using the « operator £0 write a string to a file:
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This statement writes (he string " I love C++ programming" ro (he fi le assoc ia ted with o utputFi l e . As you ca n see, the stateme nt looks like a cout statement, except the file strea m object name replaces couto H ere is a statement that writes both a suing a nd t he contem s of a variable to a file: outputFile «
"Price: " «
price:
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Writing Data to a File
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The statement above writes the strea m o f data ro outputFile exactl y as cout would write it to th e screen. Program 3-29 demonstrates openi ng a fil e, writing da ta to the fi le, and closing t he fi le.
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II This program writes data to a file. ' include <iostream> 'include <fstream> using namespace std:
int main () (
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of stre am outputF ile: output File .open( "demofile. txt" ) ;
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cout «
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Progr am 3-29
" Now writing dat a to the file. \n" ;
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II Write output File outputFile output File output File
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great names to the file « "Bach\n" i « "Beethoven \n" : « "Mozart\n" ; « "Schubert\n" ;
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II Close the file outputFile.c lose(); cout«"Oone . \n return 0 ;
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