Mailinglist Archive: opensuse-programming (53 mails)

[Hallingstad Håkon <hakon.hallingstad@xxxxxxx>]

Use 'if (c < a)' (or 'if (c < b)').

Regards,
Håkon Hallingstad

-----Original Message-----
From: Verdi March [mailto:cincaipatron@xxxxxxx] 
Sent: 7. juni 2005 06:18
To: suse-programming-e@xxxxxxxx
Subject: [suse-programming-e] Detect overflow when adding 2 unsigned int


Hi, 
 
how do I detect if an overflow in the following? 
 
unsigned int a, b, c; 
a = 0xffffffff; 
b = 0xffffffff; 
c = a + b; 
 
I understand this can be done by declaring c long long 
and check if c > (1 << 32) - 1, but I just want to know 
if it's possible with c as an unsigned integer. 
 
Will the following work for all values of a and b? 
 
if (b != c - a) 
  printf("Overflow\n"); 
 
 
Regards, 
Verdi 

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