使用 sscanf 解析 C 中的字符串

Question

The string I am trying to parse is called str1, and it contains PRETTY_NAME="Ubuntu 20.04.1 LTS"

The goal is to have one variable contain PRETTY_NAME , and the other contains Ubuntu 20.04.1 LTS . I have declared both variables as char *var1, *var2

This has to be done with the sscanf function in C.

My current code looks like: sscanf(str1, "%s[^=]^s", var1. var2); The output I am receiving is that both var1, and var2 return (null) .

What am I doing wrong?

Answer 1

the %s matches the entire string terminates at white space or \0 including = in that case, you can't use that here, and you haven't initialized any of your char buffer with a size which leads to crash or undefined behavior. here is a simplified parser.

void parse(const char* str, char* pretty, char* release) {
    int pretty_end, start, end;
    sscanf(str, "%*[^=]%n=\"%n%*[^\"]%n\"", &pretty_end, &start, &end);
    
    strncpy(pretty, str, pretty_end);
    pretty[pretty_end] = '\0';
    
    strncpy(release, str+start, end-start);
    release[end - start] = '\0';
}

int main() {

    const char* str = "PRETTY_NAME=\"Ubuntu 20.04.1 LTS\"";
    char pretty[256];
    char release[256];
    parse(str, pretty, release);

    return 0;
}