array include range from python in c++

Question

I have an array in python, which is declared as follow:

u[time][space]

My code in Python's for loop requires me to do the following:

for n in range(0,10):
    u[n][:] = 1

This colon indicates the whole range of my [space].
Now, how would I go about to use the colon (:) to indicate the whole range when doing for loop in c++?

Thanks

You might use something like auto v = std::vector<std::vector<int>>(time, std::vector<int>(space, 1)); instead. — Jarod42
– Jarod42, Commented May 4, 2017 at 14:58
this question is pretty vague. what exactly are you trying to do? if you're just trying to assign vectors a value of 1, look at constructor 4 -- otherwise, manipulating vectors takes two loops because it doesn't have slicing syntax on lists — kirinthos
– kirinthos, Commented May 4, 2017 at 14:58

Vittorio Romeo · Accepted Answer · 2017-05-04 14:58:55Z

3

for(auto& inner : u)
    std::fill(inner.begin(), inner.end(), 1);

answered May 4, 2017 at 14:58

Vittorio Romeo

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Comments

NosPix · Accepted Answer · 2017-05-04 14:58:44Z

0

Use two loops as suggested. Something like:

int n, s;
for(n=0; n<10; n++){
   for(s=0; s<space; s++){
      u[n][s] = 1;
   }
}

should work.

answered May 4, 2017 at 14:58

NosPix

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Comments

NathanOliver · Accepted Answer · 2017-05-04 14:59:32Z

0

C++ does not have an equivalent to

for n in range(0,10):
    u[n][:] = 1

You are going to have to write the loop that u[n][:] = 1 represents. Fortunately with ranged based for loops it is pretty trivial. That would look like

int foo[3][3];
for (auto& row : foo)
    for (auto& col : row)
        col = 1;

answered May 4, 2017 at 14:59

NathanOliver

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Comments

Skefrep · Accepted Answer · 2017-05-04 15:02:00Z

0

I don't remember a quick way to do it in C++. I'm afraid you'd have to loop in each table.

This would look like this (admitting that space is a known integer):

for (int i = 0; i < 10; i++)
    for (int j = 0; j < space; j++)
        u[i][j] = 1;

answered May 4, 2017 at 15:02

Skefrep

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Comments

Luke Hollenback · Accepted Answer · 2017-05-04 15:00:13Z

-1

You're going to have to use two loops. Modern C++ has some tricks up its sleeve to make initializing these loops simple, but here is a basic C example that will work anywhere:

#define TIME_MAX 100
#define SPACE_MAX 350

int u[TIME_MAX][SPACE_MAX];
int i, j;

for (i = 0; i < TIME_MAX; i++)
    for (j = 0; j < SPACE_MAX; j++)
        u[i][j] = 1;

answered May 4, 2017 at 15:00

Luke Hollenback

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