Programs for strings in QBASIC
*  U CASE $ expression
-  It converts all letters to capital letter which  is given in the expression.
CLS
INPUT "Enter an String"; a$
PRINT UCASE$(a$)
END

*  L CASE $ expression
-  It converts all letters to small letter which  is given in the expression.
CLS
INPUT "Enter an String"; a$
PRINT LCASE$(a$)
END

*  LEFT $ expression
-  It returns n characters from the left side of the given expression.
CLS
INPUT "Enter an string"; l$
INPUT "Enter how many characters wants to print"; n
PRINT LEFT$(l$, n)
END

*  RIGHT $ expression
-  It returns n characters from the right side of the given expression.
CLS
INPUT "Enter an string"; r$
INPUT "Enter how many characters wants to print"; n
PRINT RIGHT$(r$, n)
END

*  MID $ expression
-  It returns n characters from the expression to start position and up to the given length
CLS
INPUT "Enter an string"; r$
INPUT "Enter from which position want to print characters"; n
INPUT "Enter length up to which you want to print”; x
PRINT MID$(r$, n, x)
END