英文:
How to get return value by C program in python
问题
我有一个在Windows上运行的C程序，它有一个返回值的主函数。
#include <stdio.h>
int testData()
{
int testErr = 0;
// ....
return(testErr);
}
int main(void) {
int mainErr = 0;
mainErr = testData();
printf("mainerr = %d", mainErr);
return mainErr;
}
这个C代码可执行文件myTest.exe通过Python运行。
self.run_cmd = "myTest.exe " + cmd # 传递参数给C可执行文件
self.testRun = subprocess.run(self.run_cmd,
stdout=subprocess.PIPE, stdin=None, stderr=subprocess.PIPE,
bufsize=0, universal_newlines=True, timeout=100)
print(">>>>", self.testRun.stdout)
print(">>>>", self.testRun.stderr)
使用print(">>>>", self.testRun.stdout)，我在Python中没有得到C代码的返回值。
在Python中如何获取C main 返回的返回值？
英文:
I have a C(on windows) program which has a main function which returns a value.
#include <stdio.h>
int testData()
{
int testErr = 0;
// ....
return(testErr);
}
int main(void) {
int mainErr = 0;
mainErr = testData();
printf("mainerr = %d", mainErr);
return mainErr;
}
This C code executable myTest.exe is run through python.
self.run_cmd = "myTest.exe "+cmd # pass agruments to the C exe
self.testRun = subprocess.run(self.run_cmd,
stdout=subprocess.PIPE, stdin=None, stderr=subprocess.PIPE,
bufsize=0, universal_newlines=True, timeout=100)
print(">>>>", self.testRun.stdout)
print(">>>>", self.testRun.stderr)
Using "print(">>>>", self.testRun.stdout)" I am not getting the C code's return value in python.
In python how to get the return value returned by C main.
答案1
得分: 2
run 函数返回一个 CompletedProcess 对象，该对象具有一个 returncode 属性。
英文:
The run function returns a CompletedProcess object, which have a returncode property.
答案2
得分: 0
在Python中，subprocess模块监视命令的返回值（即成功为0，失败为1）。由于您从C程序返回了某个值，因此程序成功退出并返回了返回代码0。在这里，您可以在C程序中使用exit(1)来终止程序并返回退出代码1。
可以使用以下方式监视C程序的退出代码：
import subprocess
subproc = subprocess.run(<要执行的命令>, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
if subproc.returncode == 0:
logger.info('成功退出')
另一种方法是将所需的输出写入文件或数据库，然后从Python代码中读取。
英文:
In python subprocess module monitors the return value of the command (i.e. 0 for success and 1 for failure). Since you are returning some value from your C program the program successfully exited with return code 0. What you can do here is you can use exit(1) in your C program to terminate the program with exit code 1 where you want to return 1.
The exit code of the C program can be monitored using,
subproc = subprocess.run(<command to execute>, stdout=subprocess.PIPE, stderr=subprocess.PIPE,)
if (subproc.returncode == 0):
logger.info('Exited successfully')
Other way is to write your desired output in some files or DB and read that from your python code.
答案3
得分: 0
使用子进程获取的返回值将是字节。
运行后：
self.testRun = subprocess.run(self.run_cmd, stdout=subprocess.PIPE, stdin=None, stderr=subprocess.PIPE, bufsize=0, universal_newlines=True, timeout=100)
您可以捕获输出：
result = self.testRun.stdout.decode('utf-8')
此结果是一个字符串，可以进一步使用。
英文:
The return value obtained from using subprocess will be bytes.
After running :
self.testRun = subprocess.run(self.run_cmd, stdout=subprocess.PIPE, stdin=None, stderr=subprocess.PIPE, bufsize=0, universal_newlines=True, timeout=100)
You can capture the output as :
result = self.testRun.stdout.decode('utf-8')
This result is a string and can be used further.
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