linux - Some daze about the Pascal output -

platform: linux 2.6.18 x86_64

compiler: free pascal compiler version 2.2.2 [2008/11/05] x86_64

the source code is:

program main; var invalue:string; begin         (*until eof, loop continue work*)         while not eof         begin                 write('please input express: ');                 flush(stdout);                 readln(invalue);                 writeln('the expression is: ',invalue);         end;         writeln('');         writeln('exit program. bye!'); end. 

i compiled , run it. ouput like:

123 please input express: expression is: 123 234 please input express: expression is: 234 345 please input express: expression is: 345  exit program. bye! 

the numbers input. googled it, , thought because of buffer. tried add flush(stdout) or flush(output) after write. still not work well.

i hope works as:

please input express: 123 expression is: 123 please input express: 234 expression is: 234 please input express: 345 expression is: 345  exit program. bye! 

thank you! , sorry fool~

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addition: tried (thank you, aloush!)

program main; var invalue:string; begin         (*until eof, loop continue work*)         while not eof         begin                 write('please input express: ');                 flush(stdout);                 readln(invalue);                 writeln('')                 writeln('the expression is: ',invalue);         end;         writeln('');         writeln('exit program. bye!'); end. 

the result still not as:

1 please input express:  expression is: 1 2 please input express:  expression is: 2 3 please input express:  expression is: 3 4 please input express:  expression is: 4 5 please input express:  expression is: 5  exit program. bye! 

the readln still executed before first write.

by way, tries:

program main; var invalue:string; begin         (*until eof, loop continue work         while not eof         begin*)         repeat                 write('please input express: ');                 flush(stdout);                 readln(invalue);                 writeln('the expression is: ',invalue);         until eof;         writeln('');         writeln('exit program. bye!'); end. 

in case, first loop good, others still wrong.

please input express: 123 expression is: 123 234 please input express: expression is: 234 345 please input express: expression is: 345  exit program. bye! 

thank you!

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final solution: http://www.amath.unc.edu/sysadmin/doc4.0/pascal/lang_ref/ref_io.doc.html#592 it's because, eof corresponds implicit read. current code should be:

program main; var invalue:string; begin         (*until eof, loop continue work*)         write('please input express: ');         while not eof          begin                 readln(invalue);                 writeln('the expression is: ',invalue);                 write('please input express: ');         end;         writeln('');         writeln('exit program. bye!'); end. 

lastly, thank you, aloush here , keiy on csdn!

can try following?

program main; var invalue:string; begin         (*until eof, loop continue work*)         while not eof         begin                 write('please input express: ');                 flush(stdout);                 readln(invalue);                 writeln('')                 writeln('the expression is: ',invalue);         end;         writeln('');         writeln('exit program. bye!'); end.