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How to fix Error 61 in printf/StrFormat calls

AmiBroker version 6.07 has introduced a strict check for correct string formatting in printf and StrFormat functions. These functions allow to specify the string followed by the list of arguments that will be inserted into the string in places, where %f, %g or %e specifiers are entered.

This works the following way:

StrFormat example

It is important for the list of subsequent arguments to match the number of % specifiers in the string. In cases, where there is no match – AmiBroker will display Error 61 message. Strict check is required because Microsoft C runtime crashes if wrong parameters are passed. Passing on earlier version was dangerous because it would lead to random crashes now and then depending on machine configuration.

There may be the following typical problems in the code:

Example 1. Four % specifiers, five value arguments

In this example formatting string contains four % specifiers so AmiBroker expects four arguments coming later, but five are given instead (too many).

// WRONG - too many value arguments
Title StrFormat"Open: %g, High: %g, Low: %g, Close: %g"OpenHighLowCloseVolume );

Title StrFormat"Open: %g, High: %g, Low: %g, Close: %g"OpenHighLowClose );

Example 2. Five % specifiers, four value arguments

In this example formatting string contains five % specifiers so AmiBroker expects five arguments coming later, but four are given instead (too few).

// WRONG - %.0f specifier does not have a matching argument
Title StrFormat"Open: %g, High: %g, Low: %g, Close: %g, Volume: %.0f"OpenHighLowClose );

Title StrFormat"Open: %g, High: %g, Low: %g, Close: %g, Volume: %.0f"OpenHighLowCloseVolume );

Example 3. Incorrectly coded percent (%) sign

In this example user wanted to print just % (percent sign), but used % (wrong) instead of %% (correct specifier of literal percent sign).

// WRONG - to show the % sign in the output we need to use %%
Title StrFormat"Close: %g (%.1f%)"CloseSelectedValueROCClose1) ) );

// CORRECT - you should use %% to print actual percent sign
Title StrFormat"Close: %g (%.1f%%)"CloseSelectedValueROCClose1) ) );

The example 3 requires special attention, as it is a common mistake. Due to the fact that % sign is a special character, we need to use %% in our string if we want to print % sign in the output string.

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