parameter-passing

I have my array of C-Strings declared as: char *argv[MAXARGS]; MAXARGS basically just tells us how many c strings are in the array for indexing purposes. I want to pass it to this function below... int builtin_cmd(char **argv) but nothing seems to go through, I called the function like this. char *argv[MAXARGS]; builtin_cmd(argv); but once i get into the function builtin_cmd and try to print using printf("%s\n", argv[0]); it prints nothing.... but when i do this before calling the function... char *argv[MAXARGS]; printf("%s\n", argv[0]); //builtin_cmd(argv); it will print the first C string in

Given this C code: int x=12,y=10; void tswap(int pa, int pb) { int tmp; tmp=pa; pa=pb; pb=tmp; x=x+pa; x=x-pb; y++; printf("%d %d %d %d\n",pa,pb,x,y); } int main() { int a=4; tswap(x,a); printf("%d %d %d\n",x,y,a); return 0; } I have to figure out what it would print if C used call-by-reference. Here is my expectations. First of all x=12 y=10 and a=4 after tswap(12,4): pa=x=12 pb=a=4 after tmp=pa: tmp=pa=x=12 ----------- after pa=pb: tmp=x=12 pa=pb=a=4 ------------- after pb=tmp: pb=tmp=x=12 pa=a=4 after x=x+pa x=16 ------------ and after x=x-pb and y++ x=4,y=11 So I think x=4, pb=12, pa=4, y

I was trying to implement function with variable arguments but was getting garbage values as output.I have referred to this article before trying to implement on my own.Could anyone help me out with this code as I am unable to understand what's wrong in this code. /* va_arg example */ #include <stdio.h> /* printf */ int FindMax (int n, ...) { int i,val,largest,*p; p=&n; p+=sizeof(int); largest=*p; for (i=1;i<n-2;i++) { p+=sizeof(int); val=*p; largest=(largest>val)?largest:val; } return largest; } int main () { int m; m= FindMax (7,702,422,631,834,892,104,772); printf ("The largest value is: %d

This question already has an answer here: change pointer passed by value 6 answers I had a programming assignment a while back where I stumbled upon this little problem: when I gave a function a pointer as a parameter, I could not change the address it pointed at. I solved that by returning the new adress I wanted the pointer to point to. But I am still wondering why it's not possible to manipulate a pointer parameter because all memory allocating functions work with a return value as well instead of a parameter list. Was I possibly doing something wrong? Or is it really not possible to change

I would like to upsert data to a table in SQLite, but the column being updated (if the record is found) must be a running total. I am using a parameterized query, and am having trouble with the syntax. My understanding thus far is that COALESCE is the way to do an upsert in SQLite, so this is the skeleton of what I've got thus far: INSERT OR REPLACE INTO TABLE (ID, Quantity) VALUES (:ID, COALESCE(Quantity + :Quantity_change, :Quantity_change) In other words, if the record is found, add the quantity change to the current quantity, else insert the record with the quantity change as the quantity

This question already has an answer here: Swapping objects using pointers 10 answers # include <stdio.h> void mystery (int *ptra, int *ptrb) { int *temp; temp = ptrb; ptrb =ptra; ptra = temp; } int main () { int a = 2016, b=0, c= 4, d = 42; mystery (&a, &b); if (a < c) mystery (&c, &a); mystery (&a, &d); print f("%d\n", a); } My attempt : a and d are not swapped as the function mystery() doesn’t change values, but pointers which are local to the function. Can you explain in formal way, please. how works function mystery ? a and d are not swapped as the function mystery() doesn’t change values,