如何在C ++中使用printf打印数字列表？

Question

I am new learning C++ and I have basic questions and basic troubles :(

I want to print a list of numbers that are coming from the next following while condition:

int list=0;
while (list<100){
    list=list+r;
}

I want to use printf instead of cout (because I still don´t know why with cout is not working).

Can anyone help me to give me the analogous printf command to

cout<<list<<"\t";

Thanks a lot!!!

Answer 1

Here is a small sample program which counts up to 100 in increments of 10.

I use both std::cout and printf to display the value of list in each increment.

Comments added to hopefully help aid you in learning

#include <iostream>
#include <cstdio>

int main()
{
    int r = 10;

    int list=0;
    while (list < 100)
    {
        list += r;                 // this is the same as saying list = list + r, but is more succinct

        std::cout << list << "\t"; // cout is in the std namespace, so you have to prefix with std::

        printf("%d\n", list);      // the printf format specified for int is "%d"
    }
}

Output:

 10 10 20 20 30 30 40 40 50 50 60 60 70 70 80 80 90 90 100 100 

Please note that I didn't use using namespace std; at the top to import cout into the global namespace. IMHO this is bad practice, so I typically will prefer std::cout etc.

Answer 2

printf is a C function, not a C++ one, if you are learning C++ you should try to solve the problem with std::cout , which is the usual way of printing.

Anyway, printf is pretty simple to use, it takes a first argument that is a string (a C string, so an array of char with the last char as a '\\0' character) and as many parameters as you have format specifiers in your string (a format specifiers is a % char followed by another char that the function what time the variable is going to be)

Examples:

int intvat;
char charvar;
float floatvar;
char* stringvar; // to print it the last char of stringvar must be \0
printf("this is an int: %d", intvar);
printf("this is a char: %c", charvar);
printf("this is a string: %s", stringvar);
printf("this is a float and an int: %f, %d", floatvar, intvar);

For more information about printf you can refer to the reference page here: http://www.cplusplus.com/reference/cstdio/printf/