Plays the role of keyword in some programming languages. For example, in Delphi, it is the keyword of function declaration, for example, functionadd(a:integer;b:integer):integer; begin result:=a+ b;end; Function function identifier in pascal, argument type, meaning, result type
abs integer and real absolute values ??are the same as independent variables
arctan integer and real types are practical anyway type
cos integer type, real type cosine real type
exp integer type, real type exponent real type
frac integer type, real type fractional part real type
int integer, real integer partial real type
ln integer, real natural logarithm real type
pi no independent variable pi real type< /p>
sin Integer type, real type sine real type
sqr Integer type, real type square root same as independent variable
sqrt Integer type, real type square root real type
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Example: abs(-4)=4 abs(-7.49)=7.49 arctan(0)=0.0
sin(pi)=0.0 cos(pi)=-1.0 frac(- 3.71)=-0.71
int(-3.71)=-3.0 sqr⑷=16 sqrt⑷=2 Function identifier argument type meaning result type
odd integer judgment odd number Boolean< /p>
pred Finds the previous convergent independent variables of the discrete type
succ Finds the same independent variables of the discrete type
Example: odd(1000)=false pred(2000)=1999 succ（2000)=2001
odd⑶=true pred('x')='w succ('x')='y' Function identifier argument type meaning result type
chr byte character type corresponding to the argument
ord sequence number corresponding to the discrete type argument longint
round real type rounding longint
trunc real type truncation Integer longint
Example: chr(66)='B' ord('A')=65 round(-4.3)=-5 trunc(2.88)=2 Function identifier argument type meaning result type
random has no independent variable [random real number real between 0 and 1
random word [0, a random integer between independent variables) word
randomize has no self Variable initialization internal random number generator longint
upcase character type changes lowercase English letters to uppercase character type
downcase character type changes lowercase English letters to uppercase character type
SYSTEM TP's runtime library includes commonly used standard functions and procedures, which can be used directly in the program without USES statement instructions.
DOS has functions such as date, time, directory search, and program execution
CRT has functions such as screen mode control, extended keyboard codes, colors, windows, and sounds
PRINTER supports printout operations.
GRAPH is an advanced graphics software package that supports a variety of graphics adapters.
GRAPH3 is a graphics software package that implements TP3.0.
TURBO3 is compatible with the source program of TP3.0.
OVERLAY implements advanced coverage management
Common procedures and functions of SYSTEM unit
ABS(X) F finds the absolute value of a variable
ADDR (X) F Measured variable address
APPEND(F) P Open an existing text file and point the file pointer to the end of the file to add elements
ARCTAN(X) F Arctangent
ASSIGN(F,C) P Assign the external file name represented by the string C to the file variable F
ASSIGNED(X) P Test whether the pointer or variable in the program is Empty
BLOCKREAD(F,D,NUM) P Read type file.
BLOCKWRITE(F,D,NUM) P Write untyped file
BREAK P Abort or end the loop
CHDIR(PATH) P Change the current directory
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CHR(X) F Find the character with ASCⅡ code value X
CLOSE(F) P Close the file
CONCAT(S1,S2...S3) F String merging
CONTINUE P Continue looping
COPY(S,POS,LEN) F Returns a substring of a string
COS(X) F cosine Function
CSEG F Returns the current value of the CS register
DEC(X) F X:=X-1
DELETE(S,POS,LEN) P Delete A substring of a string
DISPOSE(P) P Releases a dynamic variable
DSEG F Returns the current value of the DS register
EOF(F) F Judgment Whether the file ends
EOLN(F) F Determines whether a line in the file type ends
ERASE(F) P Delete an existing external file.