thirdparty-tinyexpr/example2.c

#include "tinyexpr.h"
#include <stdio.h>

int main(int argc, char *argv[])
{
    if (argc < 2) {
        printf("Usage: example2 \"expression\"\n", argv[0]);
        return 0;
    }

    const char *expression = argv[1];
    printf("Evaluating:\n\t%s\n", expression);

    /* This shows an example where the variables
     * x and y are bound at eval-time. */
    double x, y;
    te_variable vars[] = {{"x", &x}, {"y", &y}};

    /* This will compile the expression and check for errors. */
    int err;
    te_expr *n = te_compile(expression, vars, 2, &err);

    if (!err) {
        /* The variables can be changed here, and eval can be called as many
         * times as you like. This is fairly efficient because the parsing has
         * already been done. */
        x = 3;
        y = 4;
        const double r = te_eval(n); printf("Result:\n\t%f\n", r); }
    else {
        /* Show the user where the error is at. */
        printf("\t%*s^\nError near here", err-1, "");
    }

    /* te_free should always be called after te_compile. */
    te_free(n);

    return 0;
}