j= 0 
i= 0 
delta =  0 
delta = 1 
res= 0 

j=MyConvertToMin(alltrim(time_ext))
i=MyConvertToMin(alltrim(time_out))

delta=(j-i) 
delta  = res/ 60  
delta1 = res% 60 

res=FLOOR(delta) get min

messagebox( "Work Hour is : "  + alltrim(STR(res))+  
                   " hour "  + alltrim(STR(delta1)+  " min" ))

&&******************************

function MyConvertToMin(cMixedVal)
	cNumber =  ""
	nNumber = "  "
    nCounter=0 
	cCharacter=""
	h= 0 
	m= 0 
	delta= 0 
	
    h=int(val(substr(cMixedVal, 1 , 2 )))* 60 
    m=int(val(substr(cMixedVal, 4 , 2 )))
    delta=m+h
 return delta