MQL5 compiler diagnostic
MQL5 type mismatch error is compiler code 302. The source combines values whose types do not satisfy an assignment, call, return, comparison, or object contract. Fix the declaration or operation at the boundary; use an explicit conversion only when the loss of range, precision, or enum meaning is intentional.
Open the Coding Agent and choose MQL5 from the language menu.
ENUM_TIMEFRAMES timeframe=PERIOD_H1;
int period_seconds=PeriodSeconds(timeframe);
PrintFormat("timeframe=%s seconds=%d",
EnumToString(timeframe),period_seconds);MetaEditor reports type mismatch when the source cannot satisfy the language or API contract at that location. Compile errors prevent creation of the EX5 program until they are resolved.
Start with the first error in the build output. A missing delimiter, declaration, or include can make later lines produce secondary messages that disappear after the root cause is fixed.
Compare the exact failing line with its declaration and the official reference. Keep the compiler line and column in the repair prompt or issue report.
Trace the expected type from the receiving declaration or function signature. Prefer changing an incorrectly declared variable over adding a cast. When a cast is necessary, validate range and preserve the semantic enum domain.
Compile after each coherent edit. When the first diagnostic moves or disappears, re-read the remaining list instead of applying stale fixes from the previous build.
The example preserves the enum type through the API boundary and stores the integer result separately. This is safer than treating every enum and number as interchangeable.
A clean compile or a cleared error code does not prove strategy logic, broker compatibility, backtest quality, or live-trading safety. Reproduce the result in the target MetaTrader 5 terminal and account environment.
ENUM_TIMEFRAMES timeframe=PERIOD_H1;
int period_seconds=PeriodSeconds(timeframe);
PrintFormat("timeframe=%s seconds=%d",
EnumToString(timeframe),period_seconds);Pineify can generate or revise MQL5 source and use MQL5 compilation diagnostics during the coding workflow. Keep the exact error, source location, program type, and intended behavior in the request so the change remains reviewable.
Open MQL5 Coding AgentPineify does not run your broker terminal, Strategy Tester, market data, or live orders. Validate the final program in your own MetaTrader 5 environment.
Review MQL5 AI Coding Agent capabilities
Record the message, code 302, file, line, and column from MetaEditor 5.
Open the first failing line and inspect the declaration, delimiters, include dependencies, and nearby syntax before touching later messages.
Trace the expected type from the receiving declaration or function signature. Prefer changing an incorrectly declared variable over adding a cast. When a cast is necessary, validate range and preserve the semantic enum domain.
Press F7, confirm the compiler result, then run the EA, indicator, or script in the appropriate MetaTrader 5 test environment.
The official MQL5 compilation table defines code 302 as "Type mismatch."
No. Fix the first credible root error and compile again. One malformed statement can create several downstream diagnostics.
No. Compilation validates source and type contracts. Runtime behavior, order handling, strategy logic, and broker compatibility require separate tests.
Last verified against the linked official references on . Compile and test the final source in the MetaTrader 5 build, broker, symbol, and account environment you plan to use.
Provide the exact diagnostic and intended behavior, inspect the generated change, compile it, and verify it in your MT5 test environment.
Open MQL5 Coding Agent