Help in syntax void function

[jendrin]

(Regula falsi metod. To calculate the root using 4 iterations)
I need the user to pick from problem a, b or c wherein every problem has different initial guesses.ex( prob. a Xd=1 Xu=2, prob. b Xd=2 Xu=3)
same process for all problems. And also i want to show all the values of Xd,Xu,Xr,d,u,r for the 4 iterations in tabular form.What i have done so far is this:

void falsi(double& fd, double& fu, double& fr, double d, double u, double r)
{
fd=sin(d)+cos(1+d*d)-1;
fu=sin(u)+cos(1+u*u)-1;
r=((u*fd - d*fu) / (fd - fu));
fr=sin(r)+cos(1+r*r)-1;
}

void eq(int x, int y)
{
d=1;
u=2;
cout<<"The value of Xd=1 and Xu=2\n";
for (i=4;i<5;i++)
{
falsi(fd,fu,fr,d,u,r)
if (fr>0 && fd>0)
{
r=d;
else
r=u;
}
cout<<fd<<fu<<fr<<d<<u<<r;
}

int main
{
cout<<"choose letter a, b, or c";
cin<<z; // is this correct??
if (z==a)
{
void eq(1,2);
if(z==b)
{
void eq(2,3);
else
void eq(1,4);
}
}

// Is this correct?
Btw, where can i download MSdev C++ version 5.0?

[ilikepython]

(Regula falsi metod. To calculate the root using 4 iterations)
I need the user to pick from problem a, b or c wherein every problem has different initial guesses.ex( prob. a Xd=1 Xu=2, prob. b Xd=2 Xu=3)
same process for all problems. And also i want to show all the values of Xd,Xu,Xr,d,u,r for the 4 iterations in tabular form.What i have done so far is this:

void falsi(double& fd, double& fu, double& fr, double d, double u, double r)
{
fd=sin(d)+cos(1+d*d)-1;
fu=sin(u)+cos(1+u*u)-1;
r=((u*fd - d*fu) / (fd - fu));
fr=sin(r)+cos(1+r*r)-1;
}

void eq(int x, int y)
{
d=1;
u=2;
cout<<"The value of Xd=1 and Xu=2\n";
for (i=4;i<5;i++)
{
falsi(fd,fu,fr,d,u,r)
if (fr>0 && fd>0)
{
r=d;
else
r=u;
}
cout<<fd<<fu<<fr<<d<<u<<r;
}

int main
{
cout<<"choose letter a, b, or c";
cin<<z; // is this correct??
if (z==a)
{
void eq(1,2);
if(z==b)
{
void eq(2,3);
else
void eq(1,4);
}
}

// Is this correct?
Btw, where can i download MSdev C++ version 5.0?

You have some syntax errors.

void eq(int x, int y)
{
    d=1;
    u=2;
    cout<<"The value of Xd=1 and Xu=2\n";
    for (i=4;i<5;i++)
    {
        falsi(fd,fu,fr,d,u,r)
        if (fr>0 && fd>0)
        {
            r=d;
        else
            r=u;
}
cout<<fd<<fu<<fr<<d<<u<<r;
}

You call falsi with fd, fu, fr, u, and r, but you never declared fd, fu ,fr, or r. Also, you never use x and y which are passed into the function.

if (fr>0 && fd>0)
{
    r=d;
else
        r=u;
}

The brace on that if is wrong. It should be like this:

if (fr > 0 && fd > 0)
{
    r = d;
}
else
{
    r = u;
}
 

You also did that in main.

int main
{
    cout<<"choose letter a, b, or c";
    cin<<z;    // is this correct??
    if (z==a)
    {
        void eq(1,2);
    if(z==b)
    {
        void eq(2,3);
    else
        void eq(1,4);
}
}

You never declared 'z' when you use it with cin. Also, you are checking z with the variable 'a'. You want to check it against the value 'a'. Also, you are calling your functions wrong. Delete the void before the call.

int main
{
    char z;
    cout<<"choose letter a, b, or c";
    cin<<z;    // is this correct??
    if (z=='a')
    {
        eq(1,2);
    }
    else if (z=='b')
    {
        eq(2,3);
    }
    else
    {
        void eq(1,4);
    }
}
}

Hope that helps.

PS And please put your code in code tags, it makes it easier to read.

[jendrin]

thx so much phython! sorry i'm just new here and i dont know how to create tags..
what about void(int x,int y)? i didn't quite understand whats wrong with it..can you clear it up more?thx so much again!!

btw, will this program work?

[ilikepython]

thx so much phython! sorry i'm just new here and i dont know how to create tags..
what about void(int x,int y)? i didn't quite understand whats wrong with it..can you clear it up more?thx so much again!!

btw, will this program work?

The code tags are just [ c o d e = c p p ] [ / c o d e ] without the spaces.

Your function takes two integers, x, and y. You never use them in the function. What are you trying to do?