C / C++ / MFC

29-Mar-19 5:13

Please help me with the solutions for this questions, am a beginner in C and am still learning the ropes of c programming:
1.write a method that accepts an array of integers as its parameter and returns the largest value.
2.given the <u>enum</u> below, write a method that accepts Gender as a parameter and returns the string "Sports" for male, "reading" for female. Otherwise return "acting".
3.Given the following marks results int [] marks = {23,14,32,15,17,35,19,12,21};
-write a for loop that will find the lowest mark
-write a while loop that will find the lowest marks
-write a do....while loop that will find the highest marks
the programming language to be used is c

Richard MacCutchan29-Mar-19 5:58

Richard MacCutchan

29-Mar-19 5:58

Please explain exactly what help you are asking for. But do not expect someone to do your work for you. If you do not understand the assignment then you should discuss it with your teacher.

Victor Nijegorodov29-Mar-19 6:43

Victor Nijegorodov

29-Mar-19 6:43

Is it a homework?

Member 142033272-Apr-19 4:14

2-Apr-19 4:14

it was a cat

David Crow29-Mar-19 9:24

David Crow

29-Mar-19 9:24

Member 14203327 wrote:
Please help me...

What do you have so far? Around these parts, posted code usually results in critiqued code.

Member 1420332730-Mar-19 3:52

30-Mar-19 3:52

this is the code that i had but when i run it, it gives me a 0(zero) as the answer
#include<stdio.h>
//program for finding the lowest value in an array using a for loop
int main (){
int marks [] = {20,30,40,50,60}, a = 0, b = 1 , lowest ;
for (marks[a]<marks[b];b++;){
lowest = marks[a];
a++;
}
printf("the lowest number in the array is %d", lowest );
return 0;
}

k505430-Mar-19 4:48

k5054

30-Mar-19 4:48

Member 14203327 wrote:
int marks [] = {20,30,40,50,60}, a = 0, b = 1 , lowest ;
for (marks[a]<marks[b];b++;){

Let's a look at your for loop. In C the for loop is defined as for( init; condition; increment). Where init is the initial condition of the loop, condition is the end loop condition - that is if the condition expression returns ~~true~~ false, or ~~non-~~zero, and increment is an expression that defines the next step of the loop. Lets look at your for loop:
init : marks[a] < marks[b] that's effectively a No-Op, it does evaluate to true, but it does not define the starting condition of the loop
condition : b++ I expect you know that in C false is zero and true is any non-zero value. Therefore this expression says return the value of b (= 1), then increment b, so now b = 2. ~~At this point, the end-condition of the loop is 1, or true. that means that that the body of the loop (the portion between { and } never gets executed.~~. b will continue to be incremented until it gets to INT_MAX (2147483647), at which point it will roll over to INT_MIN (-2147483646) and continue incrementing until it reaches zero. However, once the value of b reaches 5 then the expression lower = marks[a] we get the dreaded undefined behavior, which, if the computer sets itself on fire, is perfectly acceptable, according to the C standard.
increment: empty expression - no action performed. That's not necessarily wrong, there's plenty of times that you might write a for loop without a increment expression. This is not one of those times.

Here's a template for what you should do for your for loop - I'll assume that you do not have C99 or C11, so you need to declare your loop variables outside the for loop:

int a; /* index into the marks array */
int lowest = marks[0] /* initialize the lowest variable */
for( /* initial: we already know that lowest is set to marks[0], so maybe we should set our loop variable to the next index in the array */ your code here;
     /* condition: We need to iterate over the entire array, so the condition will be when the loop variable a no longer points to a valid array member.  The array as 5 elements, so the array runs from marks[0] to marks[4]. We'll need to come up with a condition expression that will return true false when a is outside the array bounds */ your code here;
    /* increment: This is where we can change the value of loop variable so the next time through the loop, we check the next element in the array */ your code here) {
   /* If marks[a] is less than lowest, then assign marks[a] to lowest */
   your code here 
}

I hope this helps you understand where you went wrong and how to fix it.

Update: Doh Got the description of the condition 100% completely backwards. Please re-read and note ~~strikeouts~~, corrections in italics follwing errors

modified 30-Mar-19 13:02pm.

Member 142033272-Apr-19 4:13

2-Apr-19 4:13

thank you, it helped me to write the program properly

David Crow30-Mar-19 5:33

David Crow

30-Mar-19 5:33

Member 14203327 wrote:
for (marks[a]<marks[b];b++;){

Among other things, this may be part of your problem. A for() loop has three components: initialization, condition, increment. Any of them can be optional. In the initialization section, you have a condition. In the condition section, you have an increment.

A more straight-forward approach might look something like:

initialize lowest to some arbitrary high number (or assign it to the 1st number in marks, and then just loop 4 times)
loop 5 times
    if the current number is less than lowest, re-assign lowest to it
repeat
print

https://www.quora.com/Difference-between-while-loops-and-for-loops-in-c-programming-language

Gerry Schmitz29-Mar-19 10:40

Gerry Schmitz

29-Mar-19 10:40

"(I) am amazed to see myself here rather than there ... now rather than then".
― Blaise Pascal

Putting declared const into a print statement

Vaclav_1-Apr-19 15:43

Vaclav_

1-Apr-19 15:43

After you figure out how to set-up the for () loop , add some debugging "scaffolding" in few places to see what your code is actually doing in each iteration of the (for) loop.
Perhaps adding some basic comments would also help.
Leaving variables intentionally uninitialized ( lowest ) is bad habit to get into, it will bite you when things get more complex.

Happy learning.

C++

//program for finding the lowest value in an array using a for loop

#define DEBUG 

int main (){
int marks [] = {20,30,40,50,60}, a = 0, b = 1 , lowest ;
for (marks[a]<marks[b];b++;){

#ifdef DEBUG 
printf (" a = %d  ", a);
#endif 
....


lowest = marks[a];
a++;
}
printf("the lowest number in the array is %d", lowest );
return 0;
}

<pre lang="c++">

SEmmett28-Mar-19 10:45

SEmmett

28-Mar-19 10:45

So, I have this snippet of code that formats an html table data cell:

if(aSensor[i].sensorSwitchState == lowState) {
 client->print("<td style='width:30px; background-color:lawngreen'>");
} else {
 client->print("<td style='width:30px; background-color:red'>"); //
}

I have each background-color:<colorname> hardcoded and the subsequent printing output is as I was expecting. However, I would like to replace the <colorname> entry - lawngreen and/or red - with a const (or #define) so that the <colorname> entry is replaced with the color name.

I've tried
#define GREEN lawngreen
...

client->print("<td style='width:30px; background-color:GREEN'>")

and that doesn't work.

I've tried
const char acolor[]="lawngreen";

client->print("<td style='width:30px; background-color:acolor'>")

and that doesn't work.

I know there has to be a way to do this, but I can't seem to figure it out. Any ideas how I go about making a declaration that will let me insert the <color name=""> in the appropriate place would be greatly appreciated.

TNX

k505428-Mar-19 11:01

k5054

28-Mar-19 11:01

Try

C++

#define GREEN "lawngreen"
client->print("<td style='width:30px; background-color:" GREEN "'>");

CPallini28-Mar-19 11:06

CPallini

28-Mar-19 11:06

This

#define GREEN "lawngreen"
client->print("<td style='width:30px; background-color:" GREEN "'>")

should work.
There might be more elegant ways, depending on print function definition.

SEmmett28-Mar-19 11:34

SEmmett

28-Mar-19 11:34

To both K5054 and Cpallini:

Thanks, that gets the job done!!
It turns out I had tried
#define GREEN "lawngreen"
but then wrote the code escaping the quotes:

client->print("<td style='width:30px; background-color:\" GREEN \"'>");

I had also tried

client->print("<td style='width:30px; background-color:"GREEN"'>");

but that didn't work. Its the space after the leading quote that does the trick.

client->print("<td style='width:30px; background-color:" GREEN"'>");

The trailing quote doesnt need a space before it.

Gotta think on that one a bit (why the quotes and their spacing is important but escaping the quotes is not) Smile | :)

k505428-Mar-19 12:01

k5054

28-Mar-19 12:01

In C/C++ consecutive string literals are catenated together

C++

cout << "hello " "world" << endl;
cout << "hello world" << endl;

both produce the same thing. I don't know why the C++11 standard requires a space between a literal and a string macro, but it probably has something to do with ambiguous parsing when no space is present.

As for the escaped quotes, if you mean

C++

client->print("<td style='width:30px; background-color:\" GREEN \"'>");

recall that \" embeds a double quote in a string, much like \n or \t embeds a new-line or a tab. If that's not what you were referring to, then maybe you could explain it better?