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/* 
HEADER:         ; 
TITLE:          BASIC like mid() string function 
VERSION:        1.0; 
 
DESCRIPTION:    provides a mid() function like BASIC mid$() with similar 
                syntax, this comes in handy when converting BASIC code 
                to C manually. 
                printf("%s\n",mid(string,10,0)); this prints the entire 
                    string beginning with string[ 10 ], since the 
                    end limit was not given (that is 0) 
                printf("%s\n",mid(string,2,5)) prints the string from 
                    string[ 2 ] to string [ 5 ] 
                A pointer to a static buffer is returned and null 
                    terminated. The original string of chars remains 
                    unaffected 
                On error, this function returns an empty string (first 
                    char is null), that is: "" 
 
KEYWORDS:       BASIC,mid,string; 
SYSTEM:         Xenix 3.4b, MSDOS; 
FILENAME:       mid.c 
WARNINGS:       compile with -dNO_PROTOTYPE if your system does not 
                support prototyping, with -dFOR_MSDOS if you are compiling 
                for MSDOS with an ANSI standard compiler. 
                Defaults assume compiling with prototypes for 
                Xenix 3.4b on Altos 2086 computer. 
 
SEE-ALSO:       demo.c; 
AUTHORS:        Vern Martin, 449 W. Harrison, Alliance, Ohio 44601; 
COMPILERS:      ECOSOFT ECO-C88, XENIX 3.4B STANDARD COMPILER; 
*/ 
 
#include "vernmath.h" 
#define LINEIN 255  /* maximum line length to be handled */ 
#define nl()    retstring[0] = (char) NULL 
 
char *mid(string,first,last) 
char *string; 
int first,last; 
{ 
/* local char */ 
    static char retstring[LINEIN+1]; 
/* local int */ 
    int x,y,len; 
    len = strlen(string); 
 
/* check for overflow */ 
    if (len > LINEIN) { 
        nl(); 
        return(retstring); 
    } 
 
/* make sure first and last set to proper values */ 
    if ( first > len-1) { 
        nl(); 
        return ( retstring ); 
    } 
    if ( last > len-1 || last <= 0 ) last = len-1; 
    if ( first < 0 ) first = 0; 
 
/* copy result into return buffer */ 
    for ( x = first,y=0; x <= last; x++,y++) retstring[y] = string[x]; 
    retstring[y] = (char) NULL; 
 
    return(retstring); 
}