scanf格式警告为双精度

Question

I'm having a small problem with a program I'm working on, I keep getting the warning format '%1f' expects type 'float *' but argument 2 has type 'double *' So I'm fairly sure it's a problem with my scanf format.

I've tried looking all over for a solution but can't seem to find one.

This function reads in two numbers.

void read(double *n1, double *d1)
{
    printf("Enter the number n1: ");
    scanf("%1f", n1);
    printf("Enter the number d1: ");
    scanf("%1f", d1);
}

Answer 1

Use scanf("%lf", n1) for double ; Note the "l" (el, not "one"). If you are new to programming, try to get familiar with documentation, eg cppreference . There you find, for example, the matrix of format and length specifies for scanf .

Have fun with learning programming, use google et al, and don't hesitate to ask :-)

Answer 2

You made a typo and then you duplicated it...

scanf("%1f", n1);

Should be written

scanf("%lf", n1);

Note the difference between l (lowercase L) and 1 (number one).

%lf stands for long float, which is not an actual C type, but a way to distinguish float ( %f ) and double ( %lf ). The l can be used with d and i to specify long int and u for long unsigned int .

These characters are difficult to distinguish, especially with fixed pitch fonts used for programming, for this very reason, one should avoid naming a variable l , ll etc. and the long integer constant 1l should be written 1L .

Answer 3

将%lf格式说明符用于双%lf数据类型。

Answer 4

Use correct format specifiers for their respective data types

• float %f
• double %lf
• int %d or %i
• unsigned int %u
• char %c
• char * %s
• long int %ld
• long long int %lld