Install GNU cflow on Ubuntu 26.04

GNU cflow is a command-line utility that analyzes C source code and produces a hierarchical representation of function calls. It can help examine relationships between functions in a C program and make the calling structure of the program easier to understand. This tutorial demonstrates how to install GNU cflow on Ubuntu 26.04.

Install GNU cflow

Update the package index to retrieve the latest package information:

sudo apt update

Install GNU cflow with the following command:

sudo apt install -y cflow

Check the installed version to verify that GNU cflow is available:

cflow --version

Testing GNU cflow

Create a sample C program for analysis:

nano main.c

Add the following code:

int is_positive(int x) {
    if (x > 0) {
        return 1;
    }

    return 0;
}

int square(int x) {
    return x * x;
}

int add(int a, int b) {
    return a + b;
}

int compute(int x, int y) {
    int sum = add(x, y);
    if (is_positive(sum)) {
        return square(sum);
    }

    return 0;
}

int main(void) {
    compute(2, 3);

    return 0;
}

Run GNU cflow against the source file:

cflow main.c

The command produces output similar to the following:

main() <int main (void) at main.c:26>:
    compute() <int compute (int x, int y) at main.c:17>:
        add() <int add (int a, int b) at main.c:13>
        is_positive() <int is_positive (int x) at main.c:1>
        square() <int square (int x) at main.c:9>

The generated listing starts with main and follows the functions invoked from it.

Uninstall GNU cflow

If GNU cflow is no longer needed, remove the package by using the following command:

sudo apt purge --autoremove -y cflow