At least this statement array->values = realloc(array->values, array->capacity); shall be rewritten like array->values = realloc(array->values, array->capacity * sizeof( Value ) ); Though it would be more safer to use an intermediate pointer like for example Value *tmp = realloc(array->values, array->capacity * sizeof( Value ) ); if ( tmp != NULL ) { array->values = tmp; … Read more
Even I get an warning a function returns an address from local variable, it compiles. Isn’t it then UB of compiler? No, but if it were, how could you tell? You seem to have a misunderstanding of undefined behavior. It does not mean “the compiler must reject it”, “the compiler must warn about it”, “the … Read more
If you have an array declared like int a[N]; where N is some positive integer value then the valid range of indices to access elements of the array is [0, N). It means that for example this for loop for(i=1;i<=10;i++) { printf(“enter 10 nos. for arr[%d] :”,i); scanf(“%d”,&arr[i]); } must look like for ( i … Read more
Yes. It is implementation-defined. According to C++03 5.8/3 which defines right-shifting: The value of E1 >> E2 is E1 right-shifted E2 bit positions. If E1 has an unsigned type or if E1 has a signed type and a nonnegative value, the value of the result is the integral part of the quotient of E1 divided … Read more
C standard says: C11: 6.5 (p2): If a side effect on a scalar object is unsequenced relative to either a different side effect on the same scalar object or a value computation using the value of the same scalar object, the behavior is undefined […] This means your program invokes undefined behavior. In the statements … Read more
First of all, C functions are call-by-value: the int x arg in the function is a copy. Modifying it doesn’t modify the caller’s copy of whatever they passed, so your swap makes zero sense. Second, you’re using the return value of the function, but you don’t have a return statement. In C (unlike C++), it’s … Read more
To see why the note in Appendix J.2 is compatible with a[b] being the same as *(a + b), consider how an expression like a[1][7] is interpreted (assuming the declaration int a[4][5], like in the appendix): a[1][7] is the same as *(a[1] + 7). Each element of the array a is a five-element array, so … Read more
will I get undefined behaviour by not including all 3 variables into every condition? The behaviour of not including all variables into every condition is not undefined by itself. Will every unaccounted for condition go into the else statement? Statement-false (i.e. the statement after the keyword else) is executed if the condition is false. what … Read more