cannot parse from string?

[addriumruss]

here is my code:

#include <stdio.h>
#include<stdlib.h>
#include <nlohmann/json.hpp>

using json = nlohmann::json;

int main(int argc, char **argv){

// create object from string literal
// parse explicitly
std::string text = "{ \"happy\": true, \"pi\": 3.141 }";
auto j = json::parse(text);

std::string str = j.dump();

printf("j=%s \n", str);

printf("happy=%d, pi=%f \n", j["happy"], j["pi"]);

return 0;
}

this is build:
g++ -Wall -std=c++14 -I./json/include -L./json/lib test4.cpp -o t4

and result:
./t4
j=
happy=25431392, pi=0.000000

[nlohmann]

For printf's %s, you need to provide a char pointer:

printf("j=%s \n", str.c_str());

In general, the mixture between the class and C-style code may need additional casting.

Could you try:

printf("happy=%d, pi=%f \n", j["happy"].get<bool>(), j["pi"].get<double>());

Or just use std::cout << "happy=" << j["happy"] ...

[addriumruss]

@nlohmann Thank you so much! I'm really appreciated!
I did it as you told and solved the problem.
j={"happy":true,"pi":3.141}
happy=1, pi=3.141000

and also got these two tip:
j={"happy":"true","pi":"3.141"}
terminate called after throwing an instance of 'nlohmann::detail::type_error'
what(): [json.exception.type_error.302] type must be number, but is string
terminate called after throwing an instance of 'nlohmann::detail::type_error'
what(): [json.exception.type_error.302] type must be boolean, but is string

it seems the value part must be the strict type match as ".get" told, when I use it to communicate to a java server which using gson or fastjson or from the web client, there would be quoted numbers. Is there any features to switch on for these situations?

[nlohmann]

The library does not perform implicit conversions such as from string to numbers.

[addriumruss]

got it.
@nlohmann , Thank you so much!