c - Why does rand() + rand() produce negative numbers? -

i observed rand() library function when called once within loop, produces positive numbers.

for (i = 0; < 100; i++) {     printf("%d\n", rand()); }

but when add 2 rand() calls, numbers generated have more negative numbers.

for (i = 0; < 100; i++) {     printf("%d = %d\n", rand(), (rand() + rand())); }

can explain why seeing negative numbers in second case?

ps: initialize seed before loop srand(time(null)).

rand() defined return integer between 0 , rand_max.

rand() + rand()

could overflow. observe result of undefined behaviour caused integer overflow.

Szoka